485 results about "Admittance" patented technology

The present invention provides a method and system of self-adaptive setting of closed-loop parameters for suppressing PV coupling harmonics, comprising: acquiring node voltages and node currents of PV grid-connected inverters; constructing harmonic coupling admittance matrix according to the node voltages and node currents; calculating an amplitude of each element in the constructed harmonic coupling admittance matrix; screening contribution sources of coupling harmonics according to the calculated amplitude of the each element; evaluating quantitatively harmonic admittance of the PV grid-connected inverter according to screened contribution sources; and, carrying out optimization iteration for double-closed-loop PI control parameters of inverter with objective of minimizing the coupling harmonics of the PV grid-connected inverter according to results of the quantitative evaluation of the harmonic admittance, to complete self-adaptive setting of closed-loop parameters for suppressing PV coupling harmonics.

The invention provides a fault ride-through control method and system for a network-forming converter, and relates to the technical field of power electronics. The fault ride-through control method of the network construction type converter comprises the following steps: determining a real-time virtual impedance value corresponding to a control loop based on a virtual admittance control module; in response to the fact that the real-time virtual impedance value is larger than or equal to the reference virtual impedance value of the control loop, transient current output by the network-building type converter is adjusted based on first-stage current limiting, and steady-state current output by the network-building type converter is adjusted based on second-stage current limiting; calculating an active power proportionality coefficient based on the real-time parameter and the reference parameter; calculating a target active power reference value according to the active power proportionality coefficient and the reference active power reference value; and executing power control based on the target active power reference value, and adjusting the output voltage of the network-forming converter. According to the method, when the power grid breaks down, the grid-forming type converter can have the functions of current limiting and transient synchronization stability improving at the same time.

The invention discloses a GaN totem-pole bridgeless PFC converter harmonic suppression method based on adaptive virtual admittance, and belongs to the technical field of converter control. The invention aims to solve the problem that LC resonance in a GaN totem-pole bridgeless PFC converter in a wide load range causes power grid voltage distortion to be converted into grid-side current harmonics. Comprising the following steps: decoupling a virtual admittance vector in a polar coordinate system, and optimizing under different load working conditions to obtain an optimal virtual admittance set; the system delay influence is compensated to ensure the robustness of the proposed method under different operation conditions; and a load power adaptive virtual admittance mechanism is constructed based on a segmented cubic Hermite interpolation method, so that suppression of network-side specific current harmonics in a wide load range is realized. The self-adaptive suppression method is used for self-adaptive suppression of the grid-side current harmonics of the GaN totem-pole bridgeless PFC converter.

The invention relates to the technical field of cable line power distribution network harmonic resonance treatment, in particular to a global and local cooperative partition cooperative resonance suppression method and device. The method comprises the steps of determining a harmonic conductance sensitivity index of each node in a power distribution network according to a target power distribution network admittance matrix parameter, and performing node region division; performing modal analysis on the admittance matrix parameters to obtain modal impedance and participation factors; determining a global optimal virtual admittance instruction value according to the modal impedance, the participation factor and the voltage distortion rate; according to the global optimal virtual admittance instruction value and the voltage distortion rate, determining a regional optimal virtual admittance instruction value in the region; and determining a harmonic compensation current value according to the regional optimal virtual admittance instruction value and the harmonic voltage. According to the method, harmonic suppression is realized for the whole power distribution network by adopting a partition and cooperation mode, and meanwhile, for background harmonic injection change, external interference such as resonance center offset and the like can be effectively overcome, so that the optimal harmonic suppression effect is realized.

The invention relates to the technical field of AC / DC module control, and discloses an intelligent control method and system for multi-mode switching of an AC / DC module. According to the method, a dynamic topology mapping model is constructed according to an impedance spectrum matrix, and a physical connection relation is converted into a node admittance relation network; generating an energy distribution state sequence based on the power fluctuation vector, and analyzing migration constraint conditions among different operation modes by adopting an association rule mining algorithm; when an operation mode switching instruction is detected, activating a node admittance relation network in the dynamic topology mapping model, and inputting a current energy distribution state sequence to an association rule mining algorithm; according to a real-time matching result of the node admittance relation network and the migration constraint condition, generating a switching control instruction containing an impedance adjustment gradient and a power distribution weight; and the power semiconductor execution unit transmits the switching control instruction to the AC / DC module. According to the method, multi-mode intelligent switching control of the alternating-current and direct-current module can be realized.

The invention discloses a power distribution network single-phase earth fault positioning method and system based on zero-sequence admittance comparison, and the method comprises the steps: obtaining zero-sequence voltage and zero-sequence current sampling values at two ends of a protected section, and determining whether to start the detection of single-phase earth fault positioning or not based on the break variable of the zero-sequence voltage; if the detection of the single-phase earth fault positioning is started, the two ends respectively calculate respective power frequency zero sequence voltage phasors and power frequency zero sequence current phasors, and send the phasors to the opposite end; respectively calculating zero-sequence admittance values of the home terminal and the opposite terminal based on the power frequency zero-sequence voltage phasors and the power frequency zero-sequence current phasors of the home terminal and the opposite terminal; and respectively calculating a differential admittance value and a brake admittance value, respectively comparing the differential admittance value with an admittance threshold value and the brake admittance value, and judging whether the protected section is a fault section based on a comparison result. The differential admittance serves as the action amount, the brake admittance serves as the floating threshold, the difference between internal and external faults is amplified, and reliability and sensitivity are effectively improved.

The invention belongs to the technical field of DC power grid short-circuit current calculation, and particularly relates to a short-circuit current calculation method for a metal backflow four-terminal bipolar DC power grid, and the method comprises the steps: S1, building an MMC equivalent model; s2, constructing and processing an equivalent circuit of a Bergeron lossy transmission line of the DC line to obtain a Bergeron two-port equivalent model of a single-phase transmission line and a Bergeron equivalent model of a three-phase transmission line; s3, establishing an equivalent model of the metal backflow four-terminal bipolar direct current power grid; s4, establishing an accompanying circuit model of the metal backflow four-terminal bipolar direct current power grid; s5, constructing a conductance matrix G, and forming a node voltage equation; and S6, according to the fault type, modifying a node admittance matrix G in the node voltage equation into an equivalent conductance matrix G ', and then solving the modified node voltage equation to obtain the branch current and the node voltage after the fault. According to the method, the problem that the short-circuit current calculation method of the metal backflow four-terminal bipolar direct-current power grid is insufficient in accuracy can be solved.

The invention discloses an impedance characteristic remodeling method, device and equipment and a medium, and is applied to the field of wind turbine generators. Wherein the corresponding rotor reference current is determined according to the electromagnetic reactive power, the active power and the corresponding power reference value; correcting the rotor current according to the rotor reference current by adopting a virtual admittance control mode, and generating a corresponding rotor voltage given value; sequentially performing differentiation, filtering and signal extraction processing on the rotor reference current and the rotor current to obtain an impedance remodeling signal; and correcting the rotor voltage given value based on the impedance remodeling signal so as to enable the corrected rotor voltage given value to serve as the control voltage of a rotor side converter in the medium-voltage doubly-fed wind turbine generator after impedance characteristic remodeling. The virtual admittance control mode and the impedance remolding signal mode are adopted to suppress the negative resistance effect of the rotor side converter in the medium-voltage doubly-fed wind turbine generator under voltage disturbance, and therefore the damping effect on external excitation in the sub-super-synchronous frequency band and the high frequency band is higher.

The invention discloses a wind power system composite oscillation suppression strategy and system based on a static synchronous compensator, and the strategy comprises the steps: firstly constructing a sequence impedance model of a GFM-STATCOM and an equivalent wind turbine generator (EWTG) based on a wind power output system containing the GFM-STATCOM; combining the impedance contribution degree beta, analyzing the interaction between the two, and determining the oscillation risk dominant factor of the sub / super-synchronous frequency band; and finally, performing frequency-band suppression: aiming at the problem of negative damping dominance of the subsynchronous frequency band GFM-STATCOM, adopting a control parameter optimization strategy based on parameter sensitivity, and reducing a reactive loop integral coefficient by increasing virtual resistance so as to reduce a negative damping range. In order to solve the problem of negative damping leading of a super-synchronous frequency band EWTG, a virtual admittance control strategy based on voltage feedforward is adopted to reduce the output impedance amplitude of a GFM-STATCOM, the leading position of positive damping of the GFM-STATCOM is enhanced, and then the negative damping of the system is eliminated. According to the invention, precise suppression of composite oscillation is realized, and the stability of a wind power sending system under a weak power grid is improved.

The invention provides a network construction type energy storage wide short circuit ratio adaptive stability control method and system, and the method comprises the steps: carrying out the calculation based on a power grid energy storage parameter, power grid impedance and energy storage impedance, and obtaining a dynamic short circuit ratio; according to the dynamic short-circuit ratio, switching the power grid operation condition mode to a power grid operation condition mode corresponding to the dynamic short-circuit ratio; in a power grid operation working condition mode, obtaining optimized virtual inductance resistance parameters or frequency-variable admittance regulator parameters; a corresponding control instruction is generated according to the virtual inductance resistance parameters or the frequency-variable admittance regulator parameters, and self-adaptive stability control is completed; real-time identification and dynamic adjustment of the power grid impedance and the energy storage impedance are achieved, traditional fixed parameter control limitation is broken through, the dynamic short-circuit ratio is obtained through calculation, the problem of power angle instability under the wide short-circuit ratio is solved, corresponding switching of power grid operation working condition modes can be conducted based on the dynamic short-circuit ratio, differential control requirements of a weak power grid and a strong power grid are considered, and the method is suitable for large-scale popularization and application. And the full-working-condition adaptive capacity is improved.

The invention belongs to the field of stability analysis of a grid-connected system of a grid-building converter, and particularly relates to a grid-building converter grid-connected resonance risk analysis method considering virtual impedance, which comprises the following steps: S1, establishing a three-phase time domain differential equation and simplifying the equation into a single-phase equivalent time domain model; converting into a harmonic state space model of the main circuit; s2, constructing a harmonic state space model of a control system comprising an active power control loop and a reactive power control loop; s3, introducing a virtual impedance control link, and correcting the voltage amplitude reference phasor output by the reactive power control loop; deriving an expression of a modulation signal disturbance phasor; s4, obtaining a complete frequency domain admittance model YGSC of the network construction converter considering the influence of the virtual impedance; an open loop gain TGFM of the grid converter grid-connected system is constructed; and S5, drawing a Nyquist curve based on TGFM, and carrying out resonance risk determination. According to the method, the interaction dynamic characteristics of the network building converter and the power grid under the influence of the virtual impedance can be accurately represented, and the resonance risk of the grid-connected system is evaluated.

The invention provides a system temporary overvoltage evaluation method under an asymmetric fault, and relates to the field of power systems, and the method comprises the steps: responding to a VSC grid-connected system AC fault, carrying out the equivalence of a VSC fault ride-through reactive power support strategy in a positive sequence network, carrying out the equivalence of a VSC unbalanced voltage suppression strategy in a negative sequence network, and carrying out the equivalence of the VSC fault ride-through reactive power support strategy in the negative sequence network; obtaining a single-machine equivalent model; the single-machine equivalent model is merged into a network admittance matrix, a corrected admittance matrix is constructed, and a corrected impedance matrix is solved; setting short-circuit boundary conditions, calculating short-circuit current increment of a fault point as an equivalent current source, solving voltage increment of each PCC point according to the corrected impedance matrix and the equivalent current source, and synthesizing three-phase voltage; and forming a TOV evaluation result based on the phase voltage maximum value of each PCC point, and calculating a voltage safety index according to the result. According to the invention, comprehensive analysis and evaluation of the temporary overvoltage risk of the new energy grid-connected system are realized.

The invention belongs to the technical field of fan torsional vibration prediction, and particularly relates to a torsional vibration prediction method, device and equipment for a net-forming type direct-driven fan and a storage medium, and the method comprises the steps: constructing a small signal model of the net-forming type direct-driven fan; based on a shafting dual-mass-block model, deducing the relation between the direct-drive fan port voltage and current signals and the direct-drive fan shafting torsional vibration when forced oscillation occurs; when forced oscillation occurs, a transfer function between different power grid node ports is obtained by constructing a wind power plant s domain node admittance model, so that required voltage and current signals of the power grid node ports are calculated, and the calculated voltage and current signals are used as input of a small signal model of a grid-constructing type direct-driven fan. And calculating the torsional vibration of the shaft system of the mesh-forming type direct-drive fan caused by forced oscillation by combining the relationship between the voltage and current signals of the port of the mesh-forming type direct-drive fan and the torsional vibration of the shaft system of the mesh-forming type direct-drive fan. The potential torsional vibration problem can be found and processed in time, and faults are avoided.

The invention provides a power distribution network broadband interference traceability method and system resistant to strong noise influence. The method comprises the steps of obtaining a voltage incidence matrix, a vector of a to-be-estimated quantity and a vector of a three-phase harmonic current; establishing a parameter estimation equation by using the voltage incidence matrix, the vector of the to-be-estimated quantity and the vector of the three-phase harmonic current, and processing the parameter estimation equation to establish a variable weight least square expression; iteratively solving parameters by aiming at the variable weight least square expression, and calculating a residual vector generated by k-th iteration; if the residual vector is within a tolerance range, outputting line parameters under harmonic waves estimated this time, obtaining self-impedance and earth admittance of each node, obtaining a harmonic wave position index by using a fuzzy logic method, inputting the harmonic wave position index into a statistical parameter calculator with abnormal values removed, obtaining a sequence value after the abnormal values are removed, and calculating a threshold value; and filtering the harmonic position index lower than the threshold value, and judging the node where the interference source is located.

The invention belongs to the field of complex electrical impedance tomography, and particularly relates to a complex electrical impedance image reconstruction method based on space-wavelet dual-domain driving. A boundary voltage signal on a sensor is mapped into an initial complex value admittance image by using a complex number Newton-Raphson method, the initial complex value admittance image is used as an input feature of an SWU-Net model to carry out spatial feature coding and wavelet frequency domain feature construction, the SWU-Net model comprises a plurality of residual four-azimuth full convolution encoders, a plurality of rswFormer modules and a plurality of decoders, and the SWU-Net model comprises a plurality of residual four-azimuth full convolution encoders, a plurality of rswFormer modules and a plurality of decoders. Wherein the encoder and the decoder construct and fuse spatial domain features and frequency domain features respectively. Meanwhile, a jump connection module for fusing double-domain features of a space domain and a frequency domain is constructed, and the jump connection module is used for fusing the space low-frequency features and the frequency high-frequency features. The method provided by the invention has better reconstruction performance in the aspects of quantitative indexes and visual visualization effects.

The invention discloses an impedance remodeling method for a grid-connected converter, and relates to the field of fire safety, and the method comprises the steps: respectively recording a virtual impedance transfer function and a virtual admittance transfer function into a current inner loop universal controller structure under a d / q coordinate system, and obtaining a series virtual impedance control structure and a parallel virtual admittance control structure; the series virtual impedance control structure and the parallel virtual admittance control structure are subjected to time domain and frequency domain conversion to obtain a series virtual impedance Norton equivalent circuit and a parallel virtual admittance Norton equivalent circuit respectively; based on the influence of virtual impedance and virtual admittance on the converter, multiple compensation links are added in a control framework of the grid-connected converter, so that the harmonic voltage and harmonic current of a grid-connected point are reduced, and the converter operates more stably.

The invention relates to a three-level SVG multistage WARD equivalent modeling method based on an L / C constant admittance model. An ANPC type three-level converter model is an important part of various types of power electronic equipment, and is applied to scenes such as a three-level static var generator (SVG) and the like. In small-step offline simulation, an existing simulation modeling technology cannot consider precision and efficiency at the same time. Aiming at the problem that the simulation speed is extremely low in an offline simulation platform, a three-level SVG electromagnetic transient simulation acceleration model equivalent to a multi-stage nested fast simultaneous solution algorithm is provided based on a device Norton equivalent circuit. Firstly, an L / C equivalent constant admittance model is used for carrying out equivalent processing on a switching device, first-time WARD equivalence is carried out, then an equivalent circuit is connected with other transformer and filter inductance circuit parts, WARD equivalence is carried out again, and finally a Norton form equivalent circuit is formed.

The invention discloses a grounding fault judgment method and system of a distribution line grounding system, a storage medium, electronic equipment and a computer program product. According to the ground fault judgment method, the ground fault judgment system determines a zero-sequence voltage abrupt change value and a zero-sequence voltage amplitude according to the collected zero-sequence voltage of the distribution line; under the condition that the zero-sequence voltage abrupt change value meets a preset zero-sequence voltage abrupt change value condition, determining a transient grounding judgment result and a zero-sequence admittance value according to the collected zero-sequence current and zero-sequence voltage of the distribution line; determining the classification condition of the zero-sequence admittance value according to the transient grounding judgment result; under the condition that the zero-sequence voltage amplitude meets a preset zero-sequence voltage amplitude condition, determining a zero-sequence admittance judgment result according to the classification condition of the zero-sequence admittance value and the zero-sequence admittance value; determining a grounding comprehensive result according to the transient grounding judgment result and the zero-sequence admittance judgment result; and determining a grounding fault condition of the distribution line according to the grounding comprehensive result and a preset grounding result condition.

The invention discloses a direct-driven fan system impedance modeling method considering frequency coupling, and the method comprises the steps: S1, obtaining a mathematical expression of a blade tip speed ratio and output power according to a wind turbine airflow model of a direct-driven fan; s2, according to equivalent circuit topology modeling under a dq coordinate system of the permanent magnet synchronous motor, obtaining an expression of electromagnetic torque and electromagnetic power; s3, according to the control structures of the machine-side converter and the grid-side converter of the direct-drive fan, modeling is carried out respectively, and an equivalent admittance mathematical expression of the machine-side converter and six disturbance admittance expressions in the direct-drive fan are obtained; and S4, based on the mathematical expressions of the output power, the electromagnetic power, the equivalent admittance and the disturbance admittance obtained in S1, S2 and S3, establishing the equivalent admittance / impedance of the direct-drive fan system. According to the method, multi-time-scale control and full-working-condition frequency domain port characteristics of the direct-driven fan system can be effectively represented, and the equivalent impedance model can accurately analyze the stability of the system.

The invention relates to the technical field of harmonic wave evaluation, and particularly discloses a follow-up network parallel system harmonic wave anti-interference evaluation method and system considering frequency coupling, and the method comprises the steps: obtaining grid-connected current data of a GFL converter and a GFM converter under different background harmonic waves, calculating the harmonic wave coupling admittance matrix of the GFL converter and the GFM converter, and calculating the harmonic wave coupling admittance matrix of the GFL converter and the GFM converter; obtaining a harmonic coupling admittance matrix of the parallel system at the common coupling point; calculating a power grid side harmonic coupling admittance matrix based on the harmonic coupling admittance matrix of the parallel system at the common coupling point and the power grid line impedance; and based on the power grid side harmonic coupling admittance matrix, calculating an evaluation index of the anti-background harmonic interference capability of the parallel system, and realizing evaluation of the harmonic anti-interference capability of the parallel system. According to the method, harmonic mutual impedance is introduced, the influence of harmonic coupling is fully considered, and the harmonic anti-interference capability evaluation precision is effectively improved in part of scenes.

The invention discloses a high-voltage direct-current cable electromagnetic transient frequency domain modeling and time domain solving method, system, medium and equipment, and the method comprises the steps: obtaining an initialization parameter of a high-voltage direct-current cable, calculating an internal impedance matrix [Zi] of a multi-layer cross-section cable body during frequency calculation, and calculating an admittance coefficient matrix of the multi-layer cross-section cable body during frequency calculation; calculating ground loop impedance [] and potential coefficient [] of the air laying cable or the direct burial laying cable, and obtaining a total impedance matrix [] and a total admittance matrix [] of the cable at the time of frequency: importing obtained multi-frequency [] and [] calculation results into a PSCAD TLine module, and realizing time domain solution of frequency domain calculation by using a vector fitting model.

The invention discloses a method for checking and evaluating a constant value of a power distribution network containing new energy, which comprises the following steps of: acquiring a description information file of electronic equipment of a relay protection device containing the power distribution network containing the new energy and an electric quantity information file of a power transmission line of the power distribution network so as to construct a power distribution network model; after setting a fault position in the power distribution network model, reading a first setting value of a relay protection device and the electrical quantity of the power distribution network, and calculating according to the electrical quantity of the power distribution network to obtain a three-sequence node admittance matrix; modifying the three-sequence node admittance matrix according to a specified fault type, and calculating a fault current value of the power distribution network according to the modified three-sequence node admittance matrix; and calculating a second setting value according to the power distribution network fault current value and the first setting value, iteratively calculating the fitness of the second setting value, and calculating a new second setting value according to the power distribution network fault current value until the fitness of the second setting value meets the requirement. According to the method, the checking efficiency is improved by automatically carrying out short-circuit current calculation, constant value adjustment and fitness evaluation.

The invention discloses a multi-converter grid-connected frequency domain stability analysis method and system based on a system admittance matrix dynamic model, and the method comprises the steps: firstly, determining a main circuit structure of a single-inverter grid-connected system and a control strategy of the main circuit structure, and building a small signal model; secondly, carrying out equivalence on an alternating-current power grid accessed by multiple converters, and obtaining a node admittance matrix transfer function of a grid-connected system and system equivalent impedance outside the parallel converter by utilizing a node voltage method; then, solving left and right feature vector matrixes L and T and modal impedance of the total equivalent impedance of the system by using a modal analysis method; and finally, applying the overall impedance stability criterion to each modal impedance, and determining the stability of the grid-connected system by judging that the slope kx of the imaginary part of the corresponding modal impedance is greater than 0 and the real part value is less than 0 in a poor damping oscillation mode. The stability criterion provided by the invention can accurately analyze the influence of multi-converter access on the stability of the alternating-current power grid, and can be widely applied to a large-scale power system to obtain a visual result.

The embodiment of the invention relates to the technical field of transformer fault detection, and discloses a transformer winding fault detection method and system based on frequency response and a medium, and the method comprises the steps: determining the equivalent inductance and equivalent capacitance of a transformer winding; and calculating a first-order grounding coefficient of driving point admittance by using the peak frequency and the valley frequency when the neutral point is grounded, and calculating a first-order open-circuit coefficient by using the peak frequency and the valley frequency when the neutral point is open-circuit. A first difference function is constructed through the equivalent inductance, the scaling rate and the first-order grounding coefficient, and a second difference function is constructed through the equivalent capacitance and the first-order open circuit coefficient. And fault detection of the transformer winding is carried out according to a comparison condition between fluctuation of the first difference function and the second difference function and a preset threshold value, and early sensitive detection is realized.

The invention relates to the technical field of electromagnetic transient simulation, in particular to an electromagnetic transient simulation system of a power system containing multiple electronic power switches, which is characterized in that numbering and topological serial number analysis are performed on multi-switch node, resistance, inductance and capacitance parameters, and a connection mapping matrix is formed by adopting impedance conversion and admittance construction modes; a sequence structure is formed by coding control variables through a genetic algorithm, a variable sequence is constructed through switching time points and topological connection, error and duration combined evaluation is executed, an optimal combination is screened, time matrix construction is carried out after energy storage voltage and filter current are collected, and a principal component vector and a covariance projection coefficient are extracted; meanwhile, an input matrix is constructed, harmonic information is fused in a unified time step, a residual network structure is introduced to carry out time-step-by-step iterative updating processing on an initial weight, dynamic adjustment is completed in combination with residual offset calculation and local error compression in each step, and a continuous and complete reconstructed waveform is output.

The invention discloses a three-phase unbalanced power flow line loss analysis method, which comprises the following steps of: establishing a power flow model of a three-phase unbalanced system based on a sequence component method; the power flow model comprises admittance matrixes respectively corresponding to a positive sequence, a negative sequence and a zero sequence, and equivalent admittance corresponding to any two of the positive sequence, the negative sequence and the zero sequence; converting the power flow model, and determining a first relational expression among the coupled positive sequence current, the equivalent admittance and the uncoupled positive sequence current, and a second relational expression among the coupled negative sequence current, the equivalent admittance and the uncoupled negative sequence current; determining a positive sequence electrical component according to the first relational expression, and determining a negative sequence electrical component according to the second relational expression; and determining the line loss of the three-phase unbalanced system according to the positive sequence electrical component and the negative sequence electrical component. According to the method provided by the invention, the accuracy of line loss analysis can be improved.

The invention belongs to the technical field of resonance stability of a power system, and discloses a high-voltage reactance configuration method for improving resonance stability of the power system, which solves the precision defect caused by neglecting voltage fluctuation in traditional modeling by establishing a fan and static var generator precise admittance model considering DC voltage fluctuation. The dq admittance model of the alternating current system is obtained according to the nodes, connected to the alternating current system, of the fan and the static var generator, general calculation of dq admittance of the multi-node alternating current system is achieved, the limitation that only single-node modeling is supported in a traditional method is broken through, the complex stability problem is quantized into an optimizable amplitude margin index, and the stability of the system is improved. A clear basis is provided for resonance stability analysis, high reactance configuration is expanded from traditional reactive compensation to resonance stability active optimization, and the resonance stability design efficiency of the new energy grid-connected system is remarkably improved.

The invention provides a stability analysis method and system for a tracking and networking inverter hybrid system and a medium, and the method comprises the steps: selecting the active power of a tracking inverter and the reactive power of a networking inverter as core variables through working condition variable dimensionality reduction; determining a working condition range in combination with capacity constraint, performing discretization processing, and calculating dq components of voltage and current of an inverter port based on a discrete working condition; discrete impedance models of the two types of inverters are respectively constructed; the influence of a phase-locked loop controller, a current loop controller and a power loop controller is considered in a following network type, and the effect of a virtual synchronous controller, a current loop controller and a voltage loop controller is included in a construction network type; and calculating a closed-loop transfer admittance matrix of the power grid through the discretized impedance of the inverter to realize stability analysis of the hybrid system. According to the method, the modeling complexity is effectively reduced, the stable working areas of the system under different working conditions can be quantified, and an accurate reference basis is provided for stable operation of the hybrid inverter system.

The invention relates to a DC power transmission system oscillation suppression method based on a matrix passivity theory. The method comprises the following steps: firstly, establishing a converter admittance matrix under a frequency coupling effect; then, constructing a stability criterion of the direct-current power transmission system based on the admittance matrix of the converter in combination with a matrix passivity theory; and finally, based on the stability criterion of the direct-current power transmission system, adding active damping and passive damping, adjusting corresponding parameters, and suppressing medium-high frequency oscillation of the direct-current power transmission system. The method can solve the problem of dependence on power grid side impedance modeling, constructs the stability criterion of the DC power transmission system by directly analyzing the admittance matrix characteristics of the converter, adapts to the complex situation when the AC grid side operation condition changes, and can completely suppress the medium-high frequency oscillation of the DC power transmission system. An unstable interval of a direct current system is transferred to a high frequency band through active damping, strict stability of the direct current power transmission system in middle and high frequency bands is achieved through passive damping, and the strategy cost is reduced.

The invention discloses a grid-connected stability analysis method for a system containing a black box converter, and belongs to the technical field of power system stability analysis. The method comprises the following steps: injecting multi-frequency-point voltage disturbance during grid-connected operation of a black box converter, and measuring current response to obtain admittance data; fitting into a frequency domain transfer function by using a vector fitting algorithm; then constructing a system admittance matrix without a black box converter based on a power system network topology, and adding a transfer function to obtain a whole system admittance matrix; and finally, solving the characteristic root by adopting an s-domain modal analysis method to judge the stability of the system, and if the system is not stable, analyzing the oscillation frequency, the participation factor and the element sensitivity, and determining a resonance suppression strategy. According to the method, internal parameters of equipment are not needed, a complete stability analysis process is provided, the resonance source can be accurately positioned, an optimization strategy is provided, and the method can be used for rapid stability evaluation of various new energy systems.