819 results about "Circulating current" patented technology

The invention relates to the technical field of cable fault monitoring, in particular to an intelligent cable fault monitoring and early warning method and system, and the method comprises the steps: detecting a sheath circulation phase angle, adjusting the frequency through offset threshold exceeding, extracting de-noising data, injecting pulses, measuring the time delay, correcting the temperature, inverting a carbonization path, matching a conductivity abrupt change generation map, and measuring the attenuation rate to update the carbonization depth. And calculating a correlation factor to trigger early warning. According to the invention, through dynamic detection of circulation phase angle offset, frequency modulation anti-interference data extraction, noise suppression, signal-to-noise ratio improvement, combination of temperature gradient and dielectric correction delay, compensation of signal temperature influence, accurate inversion of a carbonization starting point, and joint analysis of multi-band signal attenuation rate and propagation time, complex working conditions are adapted; a coupling model is established through dynamic comparison of correlation factors and threshold values, layered early warning is performed, phase correction, temperature compensation and multi-band collaborative analysis are fused, and the positioning precision and the evaluation reliability are improved.

The invention discloses a cable sheath ring current fault positioning in-loop simulation method and system based on LABVIEW. The method comprises the following steps: collecting ring current data of cable sheath monitoring points in real time under the control of LABVIEW, and carrying out digital display and graphical display; decomposing circulation data to obtain a wavelet coefficient and calculating features, and inputting a classification model to obtain a fault type when the features are abnormal; calculating a compensation coefficient considering the influence of the electromagnetic field, and calculating the position of a fault point in combination with a double-end traveling wave method; the operation model switches a typical working condition simulation mode, prediction of a Bayesian reasoning correction model is carried out, and the full-life-cycle operation state of the cable is simulated; and performing fault early warning through the LSTM model and risk assessment. The method can effectively improve the cable operation and maintenance efficiency and reliability, and is widely applied to cable fault detection and guarantee of safe and stable operation of a power system.

A method for testing sheath impedance in a high-voltage cable cross-bonding system. Three-phase current data and three-phase grounding circulating current data from a first cable body segment and a last cable body segment in cross-bonding units, and three-phase current data, three-phase grounding circulating current data, and three-phase induced voltage data from a cable body at a cross-bonding box are detected and collected, thereby directly calculating three-phase sheath impedance of the three cable segments and determining whether the three-phase sheath impedance is abnormal (step 5), thus determining whether the tested cross-bonding units have a defect. The present invention involves a simple operation, achieves an accurate testing result, and can achieve energized testing without an external excitation source. By performing real-time testing on the cross-bonding units and calculating the sheath impedance of the three cable segments in the cross-bonding units in real time, the states of the cross-bonding units can be determined in real time, which makes it possible to detect a cable fault immediately, thereby preventing a loss caused due to the cable fault.

The invention provides a high-frequency circulating current calculation method for a motor simulator cascade coupling parallel structure, and the method comprises the following steps: building an equivalent decoupling circuit model of each branch in the cascade coupling parallel structure based on the voltage relation of each branch in the motor simulator cascade coupling parallel structure, wherein the equivalent decoupling circuit of each branch comprises an equivalent voltage source and an equivalent leakage inductor which are connected in series, and the equivalent leakage inductor is determined based on self-inductance and mutual inductance of a choking coil of each branch; a plurality of duty ratio intervals are divided between 0 and 1, and the number of the duty ratio intervals is equal to the number of the branches in the cascade coupling parallel structure; and using the equivalent decoupling circuit model to calculate the high-frequency circulation of each corresponding branch when the duty ratio of the modulation signal of the motor simulator is in each duty ratio interval. According to the method provided by the invention, the high-frequency circulating current of the cascade coupling parallel structure of the motor simulator can be accurately calculated, and effective support is provided for targeted design of a high-frequency circulating current suppression scheme.

The invention provides a modularized multi-level converter current control method based on feedforward analysis. The deviation between the direct-current side voltage and the reference value is stably monitored in real time based on the direct-current bus voltage, a first waveform signal is dynamically generated, and the direct-current side voltage fluctuation range is limited. According to the circulating current interphase voltage sharing, the dynamic deviation between the actual value and the rated value is calculated by collecting the capacitor voltage actual value of the bridge arm sub-module, and a second waveform signal is generated to balance the circulating current distribution of each phase of bridge arm. The loop current suppression based on feedforward analysis generates a third waveform signal to compensate for high-frequency loop current interference through real-time comparison of theoretical modeling and actual loop current components. In the modulation wave generation process, information in all aspects is integrated to accurately control the on-off state of the sub-module, so that the operation effect of the system is improved under the complex working condition, and the real-time performance and predictability of control are considered through combination of closed-loop adjustment and feed-forward compensation, so that the effectiveness of control is improved.

The invention discloses a source network load storage coordination control system and method for high-capacity multi-network energy storage combined transportation. The system comprises a master station layer which is responsible for receiving a superior scheduling instruction, issuing an emergency control instruction, and performing economic optimization scheduling and rapid coordination control on photovoltaic and energy storage resources; the substation layer is responsible for accessing photovoltaic, load and energy storage resource information and decomposing and issuing superior instructions to realize a local frequency voltage control function; and the terminal layer is used for receiving a generator tripping command or a power regulation command issued by the emergency state monitoring device. The system can effectively improve the network-related performance of a new energy station, enhance the stability and reliability of a power grid, improve the absorption capability of new energy, and optimize the economical efficiency of the system. Through combined operation of the network construction type energy storage equipment and the new energy, effective support for the power grid is realized, the problem of coordination control of parallel operation of multiple voltage sources is solved, oscillation and circulation are avoided, and the overall performance and the power supply guarantee capability of the system are improved.

The invention relates to the technical field of cable fault diagnosis and positioning, in particular to a cable fault positioning method and system based on multi-source data space-time correlation, and the method comprises the steps: obtaining partial discharge, traveling wave and temperature multi-source monitoring data from a high-voltage cable-overhead line hybrid power transmission network; on the basis of space-time correlation analysis of partial discharge and temperature data, heat-electricity associated defect points are calibrated; comparing traveling waves of the cable and the overhead line, and identifying and inhibiting cross-domain propagation interference; positioning the traveling wave data which are not identified to obtain temporary coordinates, judging fault characteristics by fusing information such as sheath ring current and the like, and comparing the temporary coordinates with defect points to generate matching identification; and inputting multi-dimensional information such as fault features, defect matching identification and temperature into the fusion model, calculating the confidence coefficient of a fault mode, and outputting a cross validation positioning result. According to the invention, high-reliability positioning of mixed line faults and active early warning of insulation defects are realized by carrying out space-time correlation and fusion decision on multi-source monitoring quantities such as traveling waves, partial discharge, circulation, temperature and the like.

The invention relates to the technical field of converter power averaging and circulating current suppression, in particular to a power averaging and circulating current suppression method for parallel operation of a plurality of grid-forming type energy storage converters, which averages power through communication interaction and generates frequency and voltage compensation quantity by adopting a first regulator and a second regulator to realize accurate power averaging; meanwhile, the total current is measured locally, and virtual impedance feedforward control is adopted, so that rapid suppression of the high-frequency circulating current is realized. According to the invention, high-precision active power and reactive power equalization is realized, the capacity utilization rate is improved, high-frequency circulating current is effectively suppressed, loss and thermal stress are reduced, dynamic performance and system reliability are considered, a cooperative control architecture with complementary advantages is formed, adaptability to complex working conditions and system stability are enhanced, and engineering applicability is improved.

The invention relates to the technical field of parallel three-level converter control, and provides a parallel three-level converter model prediction control method and system, and the method comprises the steps: enabling a parallel three-level converter to be modeled as a series connection of an equivalent voltage source and an equivalent filter inductor according to the Thevenin theorem, enabling the parallel three-level converter to be equivalent to a five-level converter, and enabling the parallel three-level converter to be connected in parallel; a three-layer optimization control strategy is adopted; in the first layer, a candidate vector closest to a reference voltage vector is selected as an optimal five-level basic vector so as to track a parallel total output current; in the second layer, a redundant five-level voltage vector is selected to balance the neutral-point voltage; and in the third layer, selecting the candidate switching state which enables the circulating current suppression value function to be the minimum as the optimal redundant three-level switching state so as to suppress the circulating current. The method can effectively reduce output current harmonics under low switching frequency, and balance of neutral-point voltage and effective suppression of circulating current are realized to ensure safe and stable operation of a parallel converter system.

The invention discloses a modular high-voltage SVG circulating current suppression method. The method comprises the steps of obtaining and preprocessing module circulating current, voltage and state data; constructing an enhanced phase space fused with multiple physical quantities, extracting circulating current phase features and generating dynamic trend prediction data; calculating optimal feed-forward and feedback virtual impedance parameters based on phase characteristics and trend prediction; and generating a module control voltage correction value and a PWM control signal by applying a multi-time scale hybrid control strategy. Through hybrid control of phase space reconstruction of topology perception, multi-dimensional entropy analysis and stability guarantee, efficient suppression of the circulating current is realized, and the stability and robustness of the SVG system are improved.

This invention discloses a method and system for suppressing capacitor voltage fluctuations in SiC MMC submodules, belonging to the field of electronic power technology. Based on the analysis results of the optimal broadband harmonic circulating current injection boundary and order for SiC MMC submodules, an optimized model for submodule capacitor voltage fluctuations is determined that simultaneously injects 2nd, 4th, and 8th harmonic circulating currents and 3rd harmonic voltages, which can fully utilize the higher control bandwidth characteristic of SiC MMC. By solving the optimized model for submodule capacitor voltage fluctuations, the amplitude and phase of the reference values ​​of the 2nd, 4th, and 8th harmonic circulating currents to be injected, as well as the amplitude and phase of the corresponding 3rd harmonic voltage, are determined. Then, by injecting 2nd, 4th, and 8th harmonic circulating currents and jointly injecting the 3rd harmonic voltage, broadband harmonic joint injection is achieved, reducing the capacitor voltage fluctuations of the submodule and realizing a method for suppressing capacitor voltage fluctuations in SiC MMC submodules with high suppression effect.

Provided in the present disclosure are a converter system of a wind turbine generator system, and a wind turbine generator system and an offshore wind farm. The converter system comprises: a voltage source converter and a current source converter; and a converter control apparatus, which is configured to control the operation of the voltage source converter and the current source converter by means of taking into account an internal circulating current of a wind turbine generator system in voltage outer-loop control of the voltage source converter and by means of taking into account the internal circulating current in active and reactive power control stages of the current source converter.

The invention relates to the technical field of power supplies, in particular to a module power supply for communication equipment, which comprises an input filtering unit, at least two stages of power conversion units, an output voltage stabilization unit, an intelligent control module, a fault reconstruction unit and a composite heat dissipation structure, the input filtering unit is connected with the power conversion unit, the power conversion unit is connected with the output voltage stabilization unit, the output voltage stabilization unit is connected with a load end, and the input filtering unit, the power conversion unit, the output voltage stabilization unit, the fault reconstruction unit and the composite heat dissipation structure are respectively connected with the intelligent control module. The composite heat dissipation structure comprises a metal heat conduction substrate, a phase change material layer and a micro-channel liquid cooling module, the phase change material layer is arranged on the metal heat conduction substrate, the micro-channel liquid cooling module is arranged on the phase change material layer, and the metal heat conduction substrate is connected with the power device through heat conduction silica gel for heat conduction; when the fault reconstruction unit detects local failure, the damaged module is switched to be in a bypass state, current sharing parameters of the remaining modules are reconfigured, and the output power of the power supply is maintained to be not lower than 75% of a rated value. Compared with the prior art, the module power supply for the communication equipment has high-efficiency conversion and wide adaptability, and the efficiency is optimized in a full-load range; intelligent thermal management and reliability are enhanced, temperature rise control is obviously optimized, the phase change material layer absorbs transient thermal shock, temperature fluctuation is reduced, flow of the micro-channel liquid cooling module is adaptively adjusted, and power consumption is reduced; dynamic performance and stability are improved, multi-module parallel current sharing precision is improved, circulating current loss is reduced, and faults can be rapidly recovered.

The invention provides a carrier modulation method and modulation-demodulation system for an MMC circulation suppressor, and the method comprises the following steps: obtaining MMC operation log data, carrying out the spectrum analysis, and extracting the spectrum amplitude distribution characteristics; identifying a bridge arm circulation condition based on the amplitude distribution characteristics, and further detecting bridge arm load abnormity and unit energy abnormity conditions; identifying a circulating current frequency component according to an energy abnormal condition, performing electric energy quality attenuation detection and initial circulating current position tracing, and determining a circulating current generation mechanism; and finally, based on the risk assessment result and the generation mechanism data, constructing a modulation parameter, and generating an adaptive circulation suppressor carrier modulation strategy. Compared with the prior art, the method has the following beneficial effects: through modulation of the circulating current suppressor, modulation of the circulating current suppressor is more accurate, so that the problems of inaccurate analysis of a bridge arm circulating current generation mechanism and inaccurate analysis of an energy abnormal condition of the MMC unit existing in carrier modulation of a traditional circulating current suppressor are solved.

The invention relates to the technical field of battery management, in particular to a lithium ion battery power storage method and system based on a BMS architecture, and the method comprises the steps: carrying out the grouping specification division of a battery pack according to an internal resistance range, and collecting the internal resistance fluctuation amplitude and terminal voltage deviation rate of each cluster in real time under a constant charging current working condition; calculating the internal resistance sensitivity coefficient of each cluster under the corresponding group based on the parameters, so as to quantify the cluster-level circulating current risk level, and synchronously obtaining the number of batteries in the cluster, the internal resistance standard deviation and the charging current working condition; calculating a compensation priority index of the battery cluster by integrating the circulating current risk grade, the number of batteries in the cluster, the internal resistance standard deviation and the charging working condition; and the battery cluster with the highest priority is selected as a reference cluster, internal resistance difference compensation voltage regulation is performed on the non-reference cluster through the BMS, the terminal voltage of each cluster is dynamically balanced, the circulation effect is inhibited, and the stability and energy utilization efficiency of the battery pack in the power storage process are improved.

The invention is suitable for the technical field of flexible power distribution of a power system, and discloses a modular multilevel converter multi-objective optimization method, system and device based on model predictive control and space vector modulation, and a medium. Obtaining an output current reference value and a circulating current reference value; obtaining a reference voltage vector based on the output voltage reference value, and screening out a plurality of groups of redundant voltage vector sequences through a space vector diagram; performing performance evaluation through rolling optimization by combining each redundant voltage vector sequence with a multi-target cost function to obtain an optimal voltage vector sequence; and on the basis of the optimal voltage vector sequence and the corresponding duty ratio, a switching signal for driving each sub-module switching device of the MMC is generated, and multi-target cooperative control is realized. The three targets of reference output current tracking, circulating current suppression and sub-module capacitor voltage balance are met, and the dynamic response capability, efficiency and reliability of MMC system operation are comprehensively improved.

The invention provides a three-phase four-wire parallel inverter system circulating current suppression method based on 3D-SVPWM (three-dimensional space vector pulse width modulation), and the method comprises the steps: changing a zero-sequence voltage difference through changing a difference value of zero-sequence duty ratios of two inverters through a 3D-SVPWM strategy, thereby suppressing the zero-sequence circulating current in the parallel inverter system, and achieving the purpose of suppressing the circulating current in the parallel inverter system. The parallel inverter system comprises a parallel inverter circuit module, a 3D-SVPWM modulation module and a closed-loop control module. According to the method, zero-sequence circulating current suppression of the three-phase four-leg parallel inverter system can be realized, the steps are simple, the system loss can be reduced, the efficiency and reliability of the parallel four-leg inverter system can be improved, the service life of the parallel four-leg inverter system can be prolonged, and a relatively good zero-sequence current suppression effect can be achieved.

The invention provides a grid-connected circulating current suppression method and device for a grid-forming type wind turbine generator. The grid-connected circulating current suppression method comprises the following steps: acquiring an active power reference value, an active power actual value, a reactive power reference value and a reactive power actual value of the grid-forming type wind turbine generator and a three-phase output voltage and a three-phase output current of the grid-forming type wind turbine generator; the method comprises the following steps: performing proportional integral operation on an active power reference value, an active power actual value, a reactive power reference value and a reactive power actual value of a network construction type wind turbine generator, and calculating to obtain a first reference voltage; inputting a three-phase output voltage and a three-phase output current of the grid-forming type wind turbine generator set into a virtual impedance module, and calculating to obtain a second reference voltage; and providing the difference between the second reference voltage and the first reference voltage as a voltage reference to a voltage and current loop of the grid-forming type wind turbine generator so as to suppress the grid-connected circulation of the grid-forming type wind turbine generator.

The invention discloses a cooperative control method for neutral-point balance and circulation suppression of an inverter. The method comprises the following control steps: collecting three-phase current of a power grid side, and generating a three-phase bridge arm modulation signal through a grid-connected current control loop; collecting a lower half bus voltage and generating a first zero-sequence component through a neutral-point balance control loop; collecting three-phase current on the power grid side, and generating a second zero-sequence component through a circulating current suppression control loop; inputting the first zero-sequence component and the second zero-sequence component into a competition logic processing module, and generating a final zero-sequence component by using a competition mechanism based on dynamic weight distribution; and the final zero-sequence component is subjected to over-modulation processing and then superposed to a three-phase bridge arm modulation signal of a grid-connected current control loop, and then a control signal of the three-level inverter is obtained after PWM (Pulse-Width Modulation). The method has the advantages that by dynamically coordinating the midpoint balance and circulating current restraining requirements, efficient coordination of the midpoint balance and the circulating current restraining requirements can be achieved, the control complexity is reduced, and the method is suitable for low-cost industrial application scenes.

The invention discloses a dynamic virtual impedance control method for multi-machine parallel connection of a network construction type energy storage converter, and belongs to the technical field of power electronics. The method aims to solve the problem that accurate reactive power distribution, circulating current suppression, dynamic response and voltage precision are difficult to consider in a multi-machine parallel system through fixed parameter virtual impedance. A dynamic adjustable virtual impedance module is introduced into the voltage outer loop output end of each converter, and virtual resistance and virtual inductance are calculated in real time based on locally measured output current, bus voltage change rate and adjacent machine reactive power deviation information; and the average reactive power of the system is estimated through a phase synchronization mechanism under the condition of no communication so as to realize multi-machine cooperation. According to the method, the reactive power distribution error is less than 5%, the bus voltage drop is less than 3%, the high-frequency circulating current is controlled within 5% of the rated current under all working conditions, and the dynamic performance and robustness of the system are remarkably improved.

The invention discloses a high-voltage cable line parameter extraction method and system based on online monitoring. The high-voltage cable line parameter extraction method comprises the steps of listing a multi-conductor transmission line equation containing a relation between voltage phasors and current phasors at the two ends of a cable based on a multi-conductor transmission line theory; multiple groups of cable operation data are collected at the two ends of the cable, and moments with different load amplitudes are selected for each group of cable operation data; reducing orders of a chain parameter matrix in the multi-conductor transmission line equation and the voltage phasor and the current phasor of the head end of the cable to obtain a multi-conductor transmission line equation after order reduction; substituting the acquired cable operation data into the multi-conductor transmission line equation after order reduction, and solving a chain parameter matrix after order reduction through matrix operation; and solving the length of the cable line by using the chain parameter matrix and the chain parameter matrix after order reduction. According to the method, the calculation precision of the theoretical value of the sheath circulating current is improved, and the misjudgment rate and the missed judgment rate based on online diagnosis of the sheath circulating current are reduced.

The invention discloses a control method for eliminating low-frequency circulating current of a zero common-mode voltage modulation strategy. The control method is used for eliminating the inherent low-frequency circulating current problem of the zero common-mode voltage modulation strategy. Existing zero common-mode voltage modulation strategies all adopt repeated vector sequences, low-frequency circulating current is inevitably introduced, and the practicability of the method is seriously affected. Therefore, the invention provides a control method for adjusting the switching time sequence, and the method realizes the balanced symmetry of the polarity of the circulating current in any two adjacent carrier wave periods by exchanging the switching signals of the parallel bridge arms or reversing the switching signals of the same bridge arm, thereby eliminating the problem of low-frequency circulating current introduced by an asymmetric sequence. According to the method, by adjusting related bridge arm switching signals, alternating conversion of circulating current polarity is achieved, and an original vector time sequence of an existing zero common mode voltage modulation strategy is not damaged. Therefore, the method achieves the optimal common-mode voltage of an existing algorithm, and further eliminates the inherent low-frequency circulating current.

The invention provides a prediction control method and system for two parallel three-phase converters based on ring current symmetry, and the method comprises the steps: firstly, screening out an optimal vector combination beneficial to ring current suppression, enabling the vector combination to overturn the polarity of the ring current change rate in a single period, and facilitating the optimization of the peak value and the average value of the ring current; on the basis, a brand-new model prediction control set is established; then, on the basis of the provided optimal control set, the circulating current average value is incorporated into a cost function of model prediction control, the provided cost function selects an optimal vector combination in real time by evaluating circulating current average value tracking errors of all combinations in two control periods, suppression of low-frequency circulating current and elimination of direct-current components are achieved, and meanwhile, the low-frequency circulating current and the direct-current components are controlled in real time. Due to the fact that the optimal vector combination achieves loop-to-polarity single-period flipping, the method can further push the loop frequency spectrum up to a high-frequency area. According to the invention, suppression of the low-frequency circulating current is realized, and the direct-current component of the circulating current is completely eliminated.

The invention provides a modular multilevel converter current control method based on parameter identification. According to the scheme, the system gain coefficient is identified and dynamically updated on line through the recursive least square method, the current model is corrected in real time, the interference of inductance drift on control is solved, the deviation of current tracking, circulating current suppression and capacitor voltage balance is quantized in combination with a multi-objective function, and dynamic priority adjustment of a control target can be achieved through weight distribution. The switching signal is directly generated according to the control strategy corresponding to the multi-objective function, the delay of the traditional modulation link is avoided, the dynamic response speed is improved, and the target sub-module selection mechanism optimizes the capacitor voltage balance and reduces the device loss. In some embodiments, a failover function is also provided to ensure system stability under extreme conditions. While the current tracking precision is improved, multi-target collaborative optimization is realized, and an efficient and reliable technical support is provided for flexible interconnection of a new energy high-permeability power grid.

The invention discloses a power control method, system, equipment and medium for a modular multilevel converter, and belongs to the technical field of power electronics and power system application, and the method comprises the steps: collecting the bridge arm current, the sub-module capacitor voltage, the DC bus voltage and the AC side power of the modular multilevel converter; calculating a power error according to the AC side power and a power reference value, and calculating a sub-module capacitor voltage error according to the sub-module capacitor voltage and a voltage reference value; constructing a Lyapunov function comprising a plurality of control targets, wherein the Lyapunov function comprises a power error term, a sub-module capacitor voltage error term, a circulating current suppression term and a total energy balance term; and determining a control law on the basis that the Lyapunov function meets a stability condition, and controlling the modular multilevel converter according to the control law. According to the method, the coupling control problem of multi-terminal direct current system power distribution and sub-module energy balance is considered and improved.

The invention discloses an optimal switch time sequence design and modulation method for single-phase circulating current suppression of two parallel converters. The method comprises the following steps: firstly, screening 32 switch combinations which only introduces a certain phase of single-phase circulating current or does not introduce any single-phase circulating current from all 64 switch state combinations; secondly, designing a switching time sequence corresponding to the whole vector plane by using 32 switch combinations and considering the balance and switching times of single-phase circulating current in a switching period; in view of mutual overlapping of the time sequence modulation areas, single-phase circulation peak values of the time sequences are further compared to determine the optimal modulation areas, and then in view of redundancy of the time sequences in the optimal modulation areas, single-phase circulation effective values of redundant time sequences are further compared, and final sector division is determined according to the minimum effective values. And finally, designing action rules of modulation waves and carrier waves corresponding to each time sequence. The method solves the problem that an existing modulation method does not suppress the high-frequency single-phase circulating current of the two parallel converters.

The invention discloses a distributed cooperative voltage control method for a hybrid flexible traction substation group, and aims at solving the problems of output voltage cooperation, no-load circulating current suppression and multi-substation load distribution during networking operation of a plurality of hybrid flexible traction substations (HFTSS). Rapid synchronization of output voltage phases of the substations is achieved by introducing an average consistency algorithm, and nearby distribution of train loads among the traction substations is achieved by combining self-adaptive virtual impedance. According to the method, the capacity of the hybrid flexible traction substation for coping with the dynamic change of the external power grid voltage phase can be effectively enhanced, the loss of a contact network is reduced, the regenerative braking energy utilization efficiency is improved, and a feasible path is provided for large-scale application of a low-cost hybrid flexible traction power supply system and improvement of a cooperative control technology system.

The invention relates to the technical field of network construction type converters, in particular to a multi-machine parallel operation circulating current suppression method and system for a network construction type converter. By dynamically adjusting control parameters, cooperatively adjusting current and voltage and introducing a high-frequency impedance adjusting mechanism, generation of circulating current can be accurately inhibited in real time, and by obtaining the high-frequency impedance characteristic and the circulating current amplitude of each converter and generating the corresponding high-frequency impedance adjusting reference, the high-frequency impedance adjusting reference can be accurately adjusted. A high-frequency dynamic impedance adjusting model can be constructed according to power flow data, impedance parameters are further optimized, it is ensured that voltage output of each converter is kept consistent in a parallel system, and therefore the circulating current problem caused by voltage differences is avoided; ring current generation can be effectively reduced, and the electric energy quality and power distribution precision of the system are improved.

The invention provides a grid-connected and off-grid mode switching control method and device and an energy storage parallel operation system, and relates to the technical field of energy storage systems.The method comprises the steps that if the energy storage parallel operation system is not connected to mains supply within a preset voltage range, the energy storage parallel operation system is controlled to enter an off-grid mode; based on the first voltage characteristic information of the energy storage converter host, controlling the energy storage converter slave to adjust the first voltage parameter; if the electric supply in the preset voltage range is connected to the energy storage parallel operation system, controlling the energy storage converter host to enter a tracking pre-synchronization mode from an off-grid mode, controlling the energy storage converter host to track the electric supply and sequentially adjust the second voltage parameter, and controlling the energy storage converter host to track the energy storage converter host and sequentially adjust the third voltage parameter; and controlling the energy storage converter host and the energy storage converter slave to enter a grid-connected mode at the same time. According to the technical scheme, it is ensured that the voltage parameters of the host and the slave are consistent, parallel operation circulating current oscillation can be avoided to a great extent, and the possibility of system faults is reduced.

The invention discloses a method for determining control parameters of a network construction type wind-solar hybrid grid-connected system and electronic equipment. The method relates to the technical field of new energy control, and comprises the following steps: constructing a target function based on first control parameters corresponding to a plurality of units in the wind-solar hybrid grid-connected system; optimizing the first control parameter by taking a minimum function value of the target function as a target to obtain an optimized first control parameter; on the basis of the optimized first control parameters, second control parameters corresponding to the multiple units are optimized, and optimized second control parameters are obtained; and based on the voltage deviation, the angular frequency deviation and the dynamic compensation factor corresponding to the plurality of units, optimizing the third control parameters corresponding to the plurality of units to obtain the optimized third control parameters. According to the method, the technical problems of non-uniform reactive power distribution, serious circulating current and low dynamic response speed caused by different new energy unit types and line equivalent impedance differences are solved.