44 results about "Grid impedance" patented technology

The invention discloses a virtual synchronous generator control method for improving power transmission capability, which is characterized in that the traditional virtual synchronous generator control is composed of a power outer loop and an inner loop formed by voltage and current double closed loops. A reference voltage generated by a power outer loop subtracts a grid-connected point voltage and then is input into a current feed-forward compensation calculation module to generate a current feed-forward compensation value, the current feed-forward compensation value is superposed on a current given value output by a voltage controller, and the superposed value is used as a total current given value of a current controller. Compared with traditional virtual synchronous generator control, the method has the wide-range adaptive capacity of power grid impedance, and the limit power transmission capacity of active power of a grid-connected inverter can be remarkably improved.

The application discloses a variable-weighting fusion control method based on voltage source and current source double-source fusion, and belongs to the electrical engineering field.The method is realized through the following steps: firstly, a short-circuit ratio is calculated based on grid impedance to obtain a first initial weighting fusion factor of current source type control; secondly, an inertia ratio is calculated based on grid inertia support demand to obtain a second initial weighting fusion factor; then, local sensitivity weights are obtained by derivation of the two initial factors to obtain an initial double-source fusion factor which is self-adaptively adjusted according to grid state; finally, the initial double-source fusion factor is optimized and corrected in combination with node active regulation capacity and operation economy, safety and other strategy factors.The application can self-adaptively adjust the control fusion proportion of voltage source and current source, realizes smooth transition and stable operation of grid-connected inverters under different grid conditions, and improves the stability and self-adaptability under complex disturbance scenarios.

This invention relates to a quantitative evaluation method for the control performance of grid-connected converters from a stability perspective, belonging to the field of power systems. First, based on a single-phase equivalent model of the grid-connected converter, the modulation voltage is solved. The necessary and sufficient conditions for the existence of real solutions are used to derive the power flow solution boundary, and the voltage over-limit boundary is established in conjunction with modulation ratio constraints, defining the theoretical operating domain of the converter. Based on the theoretical operating domain, a small-signal state-space model is established by combining the main circuit topology and the control system. By analyzing the pole distribution of the converter under different grid impedances, its actual stable operating domain is determined. Finally, by calculating the area ratio of the actual stable operating domain to the theoretical operating domain, a quantitative characterization of the converter's control performance under varying operating conditions is achieved. This method constructs the actual stable operating domain of the grid-connected converter and quantifies the control performance using the area coverage ratio index. This provides a quantitative theoretical benchmark for evaluating its robustness in weak grid environments and guiding parameter optimization design.

The application discloses a large data optimized nonlinear cooperative control method and system of a converter station, and relates to the technical field of converter station control. The method comprises the following steps: obtaining real-time voltage and real-time current of a target converter station grid-connected point, and calculating real-time power grid impedance and impedance fluctuation rate; identifying the current power grid working condition type according to the impedance fluctuation rate; when the working condition is identified as a disturbance working condition, taking the real-time power grid impedance as input, and obtaining preliminary virtual inertia parameters and preliminary damping parameters through a double-branch cooperative regression network; based on the real-time power grid impedance and the impedance fluctuation rate, performing nonlinear correction on the preliminary virtual inertia parameters and the preliminary damping parameters to obtain target virtual inertia parameters and target damping parameters, generating control output, performing amplitude limiting processing through a saturation function to obtain nonlinear cooperative control instructions, and driving the converter station to perform flexible synchronous output. The application realizes real-time adaptive optimization of virtual inertia and damping parameters under weak power grid working conditions, and suppresses transient overshoot, oscillation and harmonics.

This invention discloses a general testing device and method for the weak grid adaptability of power electronic grid-connected equipment, including a converter module, a main control module, an input transformer, and an output transformer. The converter module includes a rectifier circuit unit and its filter circuit, and an inverter circuit unit and its filter circuit. The main control module controls the converter module and includes a rectifier control unit, an inverter control unit, and a host computer that are communicatively connected to each other. The rectifier control unit is connected to the rectifier circuit unit, and the inverter control unit is connected to the inverter circuit unit. The rectifier control unit and the inverter control unit receive and execute input commands from the host computer to adjust the operating state of the converter module. The inverter control unit is based on the equivalent grid impedance transfer function of a generalized second-order integrator. Using this invention, a wide-frequency domain simulation of AC grid impedance can be achieved, greatly improving the test accuracy.

This application relates to a feedforward-enhanced robust grid-connected control method for energy storage converters under wide grid impedance conditions, belonging to the field of power electronic control technology. This method transforms the current loop PI parameter design problem into optimizing the feasible stability region of the current loop controller. With the goal of maximizing the common adaptability of the stability region under different grid impedance conditions, it calculates the optimal feedforward coefficients and further calculates a set of current loop PI parameters that can cover wide grid impedance variations and possess high stability. Ultimately, it achieves feedforward-enhanced robust grid-connected control of energy storage converters under wide grid impedance conditions, fundamentally overcoming the blindness and inefficiency of traditional empirical parameter tuning, and significantly improving parameter design efficiency, overall system stability, and grid adaptability.

The present application relates to a kind of weak power grid under converter output power promotion method, by collecting in different current instruction under grid point voltage and grid current, a set of arrays characterized by grid impedance is calculated, select middle several data to obtain average, obtain the variable of characteristic grid impedance, establish the active current model corresponding to maximum power, obtain the active current value after the first iteration, then active current value is brought into the reactive current model corresponding to maximum power, obtain the reactive current value after the first iteration;Again, reactive current value is brought into the active current model, and the second iteration is carried out, so on and so forth, until the error of two iterations is less than set value, then stop iteration, obtain the reactive instruction required by converter output rated power under current grid impedance.The present application does not need to increase additional reactive compensation device, utilizes the control advantage of converter itself to carry out reactive compensation, improves the power transmission capacity of device, method is simple, applicable to engineering application.

The present application relates to the field of distributed power grid connection technology, specifically to a power distribution box coordination control method and system for distributed energy access, comprising the following steps: collecting public connection point three-phase voltage and current data to generate amplitude and power sequence, using sliding window difference operation to obtain the change, dividing the voltage amplitude change by the power change to generate the sensitivity coefficient, calculating the coupling deviation of the coefficient and the ideal value, generating a virtual inductance coefficient through an integral model, combining the current to calculate the virtual inductive voltage drop, and correcting the reference voltage command to construct the pulse width modulation signal. In the present application, the sensitivity coefficient reflecting the strength of the power grid is obtained, the virtual inductance coefficient is dynamically generated by using the deviation to calculate the virtual voltage drop and correct the command, the inductive impedance characteristics are simulated without physical cutting, the voltage flexible support is realized, the power supply interruption hidden danger is eliminated, and the adaptive ability to the power grid impedance change and the operation stability are improved.

This application relates to a method, apparatus, and device for grid impedance detection and power quality optimization in a grid-connected inverter. The method includes: performing a first impedance estimation of the grid based on background harmonics at the grid connection point to obtain an impedance estimate; obtaining a disturbance amplitude parameter based on the impedance estimate, which is negatively correlated with the impedance estimate; when the disturbance amplitude parameter is zero, performing a first impedance estimation based on the background harmonics to obtain an updated impedance estimate; when the disturbance amplitude parameter is not zero, controlling the inverter to inject a disturbance signal into the grid based on the disturbance amplitude parameter; after injection, performing a second impedance estimation of the grid based on current data, voltage data, and disturbance frequency at the grid connection point to obtain a second impedance estimate; and returning to the step of obtaining the disturbance amplitude parameter based on the updated impedance estimate. This method enables high-precision detection of grid impedance while ensuring system stability.

This invention relates to the field of carbon electricity dispatching technology for virtual power plants, and discloses a method and system for carbon electricity dispatching of virtual power plant microgrids based on spatiotemporal loss modeling. The method includes: constructing a spatiotemporal coordinate system for carbon quota loss and defining a loss shadow region by integrating grid impedance data, topology relationships, and delay confirmation cycle parameters; mapping inter-regional dispatch requests to directed dispatch line segments within the coordinate system, and obtaining the loss ratio by calculating the geometric intersection of this line segment and the loss shadow region; combining real-time carbon prices and electricity prices to calculate the net hedging profit of carbon quotas after deducting losses, and determining the generation of dispatch instructions accordingly. This invention integrates physical line losses and time delays into a unified geometric model for quantification, eliminating the mapping deviation between book quotas and actual verified quotas, and ensuring the accurate execution of hedging dispatching.

This invention discloses an adaptive frequency and voltage active support method for energy storage that considers active power limits. Addressing the problem that traditional low-voltage ride-through strategies prioritize reactive current injection, leading to a significant reduction in active power and threatening system frequency stability, this method first calculates the optimal voltage support current angle based on grid impedance parameters and then calculates the optimal active power output current angle through coordinate transformation. Next, it calculates the active power output at the current angle. If it is less than the maximum active power limit, it outputs at that angle; if it exceeds the limit, it adaptively adjusts the output current angle to approach the optimal voltage support current angle until the power constraint is met. This invention can effectively coordinate active power support and voltage support during voltage faults, while fully utilizing the current capacity and active power limits of the voltage source converter.

The application discloses a non-ideal power grid impedance detection method based on an extended state observer, which comprises the following steps: 1, collecting three-phase voltage signals of a grid-connected point, and observing grid-connected point currents on line based on an extended state observer; 2, extracting power grid fundamental wave components through an improved phase-locked loop structure of a double second-order generalized integrator, and realizing adaptive tracking of a power grid frequency; 3, performing differential processing on the power grid original signals and the extracted fundamental wave components, and extracting target harmonic components in the residual signals through a double second-order generalized integrator; and 4, calculating the power grid impedance based on the voltage and current harmonic information. The application can realize accurate identification of the power grid impedance under the conditions of power grid frequency fluctuation and existence of background harmonics while reducing current sensors.

This invention discloses a broadband oscillation suppression method for grid-connected energy storage systems, belonging to the field of power electronic converter control technology. This method acquires grid-connected voltage and current signals in real time, analyzes the oscillation energy of each sub-band using a sliding window FFT, and when broadband oscillation is detected, uses the center frequency of the sub-band with the largest oscillation energy as the target frequency. It identifies the grid impedance and converter impedance online and calculates the impedance ratio. Then, based on the impedance ratio magnitude, it adaptively adjusts the virtual impedance parameters to reshape the converter impedance characteristics and suppress oscillation. This invention uses the "sub-band with the largest oscillation energy" as the trigger condition to avoid full-band scanning and uses the "impedance ratio magnitude" as the adaptive update variable. It can suppress broadband oscillations of 2.5Hz to 1000Hz within 30ms, is suitable for extremely weak power grids with SCR < 1.5, and consumes less than 3% of DSP computing power.

The application discloses a kind of network type converter adaptive control method based on bus voltage synchronization, including based on bus voltage synchronization link, band pass filter adaptive parameter adjustment link and initial phase generation link.First, based on system closed-loop transfer function calculation closed-loop pole determines low-frequency oscillation frequency, and accordingly designs band pass filter;DC bus voltage deviation is handled in parallel by proportion controller and adaptive band pass filter, constitutes based on bus voltage synchronization link.Second, in the process of operation, real-time monitoring grid impedance variation and bus voltage low-frequency oscillation frequency deviation, by online parameter identification and spectrum analysis dynamically updates band pass filter parameter, realizes the adaptive adjustment of additional damping.In addition, introduce initial phase generation link to give converter initial phase, to realize the active output of system initial time, ensure fast grid connection.The method of the application can inhibit new energy grid-connected system low-frequency oscillation, improve system stability.

The application relates to the technical field of grid-connected inverter control, in particular to a grid impedance identification method of a single-phase grid-connected inverter, an inverter and a storage medium. The identification method comprises the following steps: determining a twice-frequency ripple voltage component contained in a single-phase grid-connected inverter bus capacitor voltage; processing the twice-frequency ripple voltage component through a voltage outer loop controller to obtain a twice-frequency ripple current component introduced in a grid-connected current amplitude reference; multiplying the grid-connected current amplitude reference containing the twice-frequency ripple current component and a grid voltage phase signal to generate a grid-connected current reference containing a thrice-frequency component; establishing a closed-loop transfer function of the grid-connected current to the grid-connected current reference and a grid impedance solving model; extracting the amplitude of the thrice-frequency component from the grid-connected current obtained through sampling and substituting the amplitude into the grid impedance solving model to calculate the grid impedance value. The method of the application realizes complete disturbance-free and extremely small calculation amount grid impedance online identification.

The present application relates to the technical field of power quality treatment, and provides a power grid impedance adaptive power quality compensation system based on perturbation injection, which comprises a grid-connected point voltage and current collection terminal, a perturbation injection terminal, a frequency domain separation and background harmonic cancellation terminal, a power grid impedance online identification terminal, a compensation instruction generation terminal and a collaborative compensation execution terminal; the power grid impedance online identification terminal is used for calculating equivalent impedance parameters of the grid-connected point in each frequency band according to the frequency band response data and constructing a power grid impedance spectrum; the compensation instruction generation terminal is used for generating a compensation instruction based on the power grid impedance spectrum and real-time power quality indexes obtained from the real-time sampling data; and the collaborative compensation execution terminal is used for executing parallel compensation and / or series compensation according to the compensation instruction. The present application has the effect of improving comprehensive power quality treatment under complex working conditions.

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 application discloses a new energy photovoltaic inverter energy conversion control system and relates to the technical field of new energy power generation grid connection. The system comprises the following modules: a signal acquisition module, which acquires grid-connected current instructions, grid voltage and current feedback signals; a virtual impedance generation module, which generates synchronous virtual impedance reference signals based on the grid voltage, wherein the virtual resistance component is negative to provide active damping; a grid working condition monitoring module, which monitors the voltage distortion rate and the frequency fluctuation rate to determine the grid working condition; a dynamic instruction generation module, which dynamically increases the inductance component weight in the virtual impedance signal according to the disturbance amplitude when the grid is in a non-ideal working condition, performs enhancement processing on the dominant disturbance type, and then superimposes the current negative feedback to the current instruction to generate a dynamic grid-connected current instruction; and a closed-loop control and driving module, which generates a switching driving signal based on the dynamic instruction and the feedback signal. The application can adapt to grid impedance changes and severe working conditions, and can improve grid stability and current control quality.

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 present application relates to the field of wind power converter compensation control, and provides a wind power converter grid-connected point harmonic adaptive compensation control method and system, which realizes zero-intrusion online identification of grid harmonic impedance by coordinate transformation and target harmonic component extraction on grid-connected point voltage and current signals; based on this, the identified grid harmonic impedance estimation value is used to adaptively calculate the proportional and integral gains of harmonic compensation in combination with the preset system target dynamic performance; finally, the adaptive gains are used to generate and superimpose harmonic compensation instructions to adjust the output voltage of the converter. In this way, the wind power converter can dynamically adjust its parameters when facing complex and variable grid impedance, thereby effectively avoiding the problem of compensation effect deterioration or even resonance caused by grid impedance changes, greatly improving the robustness and stability of harmonic suppression, and ensuring the power quality of the wind power grid-connected system under various operating conditions.

The application discloses a harmonic phase synchronization method and device and a storage medium, and relates to the technical field of power grid impedance identification. In view of the problem that when an active method is used to obtain power grid impedance for a multi-inverter system, an additional communication module and communication interconnection line such as a GPS system need to be used, a harmonic phase synchronization method is provided. A state flag signal that periodically changes is generated based on the period change of a fundamental wave signal in a master inverter. The state flag signal can represent the period change of a first harmonic signal in the master inverter. Then, after the state flag signal is sent to a slave inverter, the slave inverter can complete phase adjustment of a second harmonic signal generated by the slave inverter based on the signal, so that the second harmonic signal is kept synchronous with the harmonic signal of the master inverter. Moreover, the state flag signal used by the method is simple in form, and no additional communication module such as a GPS and no additional communication interconnection line are needed, so that the method is more practical in engineering.

In some aspects, the techniques described herein relate to a method including: receiving a data stream from one or more power plants at the same location by a computing device; based on the received data stream, determining a grid impedance of the one or more power plants with respect to a grid by the computing device; based on the received data stream, determining power plant control parameters and communication delay for each of the one or more power plants; and modeling the integrated system consisting of the one or more power plants and the grid based on the determined grid impedance and the power plant control parameters by the computing device.

This invention discloses an adaptive control method and system for active power ramp rate, belonging to the field of new energy power system control technology. It addresses the problem that traditional control strategies in weak grid environments only consider the short-circuit ratio while ignoring impedance characteristic differences. The method includes real-time acquisition of grid node parameters to calculate the short-circuit ratio; calculation of a dynamic stability index including a control bandwidth limitation coefficient and a dynamic response delay coefficient based on the impedance ratio; construction of a voltage sensitivity model based on the short-circuit ratio; and adaptive generation of differentiated ramp rate commands for different regions. This invention explicitly utilizes grid impedance characteristics to correct the control bandwidth, significantly improving ramp efficiency in resistive weak grids through physical damping, and automatically tightening the bandwidth to ensure stability in inductive weak grids. This method effectively solves the contradiction between voltage instability and limited regulation capacity caused by grid strength differences within new energy bases, significantly improving the system's robustness and absorption capacity.

The application discloses a grid-connection impedance self-adaptive regulation grid-connected inverter control method, which comprises the following steps: detecting grid-connected current and output voltage, performing coordinate transformation and power calculation, and obtaining an initial reference value of grid-connected voltage through power synchronous control; obtaining a nonlinear equation set about grid impedance by using collected grid-connected current, output voltage and calculated active and reactive power of the inverter, realizing real-time identification of the grid impedance through genetic algorithm, and then virtually outputting an impedance at an output port of the inverter through a virtual impedance algorithm, so as to self-adaptively regulate the grid-connection impedance between the inverter and the grid to an expected value. The application can self-adaptively regulate the grid-connection impedance between the grid-connected inverter and the grid, thereby ensuring that the grid-connected inverter can reliably and stably operate under strong and weak grid working conditions.

The present application relates to a kind of LCL type active power filter composite active damping optimization control method, including inverter side current active damping optimization control and grid voltage active damping optimization control.The beneficial effects of the present application are: the present application obtains the wide active damping boundary close to Nyquist frequency using the inverter side current active damping optimization control based on cascaded resonant controller, and has accurate adjustment ability to fundamental current component, to ensure the stable operation of system when grid impedance fluctuates in a large range.In addition, the present application also uses the grid voltage active damping optimization control based on weighted proportional order reduction generalized integrator, solves the potential instability risk caused by the phase margin reduction of active power filter harmonic control unit due to large grid impedance.In summary, the present application effectively improves the weak grid adaptability of LCL type active power filter.

The application discloses an active damping virtual resistance adaptive method and system based on a linear assumption, and the method comprises the following steps: in the current iteration period, the harmonic voltage measured value at the common connection point of the active damping device is acquired, the absolute error between the harmonic voltage measured value and the harmonic voltage target value is calculated, if the error amount is less than or equal to the error threshold, it is determined that the system has converged, and the final setting value is output; if the error amount is greater than the error threshold, it is determined that the system has not converged, a theoretical straight line is formed by the connecting line of the coordinate origin and the current working point, based on the linear relationship corresponding to the straight line, the next iteration virtual resistance value that makes the harmonic voltage close to the target value is calculated through the variable step adjustment strategy, and the next iteration period is entered, and iteration is continuously carried out until the system converges; the application has the advantages that the application does not depend on the power grid impedance model, has the online adaptive capacity, can be quickly and accurately set, and effectively suppresses the power system harmonic resonance.

The invention relates to the technical field of network construction type converters, and discloses a network construction type energy storage converter control method, device, equipment and medium, and the method comprises the steps: obtaining a power grid impedance parameter and charge state data of each energy storage unit through monitoring and converting three-phase voltage and current signals of a grid-connected point, generating a virtual impedance compensation voltage and a power correction signal; and the reference voltage is superposed to a basic voltage reference of the virtual synchronous generator to form a corrected reference voltage. And then a modulation signal is generated by adopting voltage outer loop-current inner loop double closed loop control to drive a converter to output, so that self-adaptive adjustment and balanced distribution of active power of each parallel energy storage unit are realized. In a weak power grid environment, the voltage supporting capability and the dynamic stability of the system can be improved, and the over-discharge of the SOC unit in the low state of charge is avoided.

This application discloses a PLC parameter tuning method and system based on online grid impedance identification. It dynamically locks sensitive frequency bands such as LCL resonance and crossover frequency through a key frequency adaptive selection mechanism and tracks grid resonance drift using historical data. Multi-frequency composite disturbance injection and Goertzel parallel demodulation technology are employed to efficiently extract discrete complex impedances at key frequency points. Based on this, the grid model parameters are identified using the least squares method, thereby reconstructing a continuous impedance spectrum across the entire frequency band, effectively overcoming the information loss problem caused by discrete measurements. Combining the reconstructed impedance spectrum with the inverter model, the system open-loop transfer function is constructed to accurately calculate the stability margin, and the proportional and integral gains of the PLC controller are adaptively tuned accordingly. This achieves accurate matching and robust control of complex grid characteristics under limited computing power.

The application discloses a wind power base phase modifier voltage reactive power coordination control system, relates to the technical field of power system operation and control, and comprises a data acquisition and processing unit, a data analysis unit and an intelligent adjustment unit. Under a steady state condition, the application creatively adopts the strategy of preferentially scheduling wind turbine generators and SVG and controlling a synchronous phase modifier to be in a low output state, ensures that the synchronous phase modifier is not occupied in a normal state, thereby maximally plays the instantaneous overload capacity of the synchronous phase modifier in the moment when a power grid fault occurs, effectively overcomes the control instability risk caused by impedance fluctuation of a weak receiving end power grid based on dynamic sensitivity matrix control, simultaneously constructs a multi-time scale and multi-device coordinated transient overvoltage defense system, greatly improves the fault ride-through capacity of the wind power base, can realize real-time sensing of actual working conditions of each reactive power source, and precalculates the steady state adjustment capacity and transient overload capacity margin before generating an instruction.