27 results about "Short circuit ratio" patented technology

This application relates to the field of power system stability control technology, specifically to a method and system for online stability assessment and control of hybrid systems based on an improved short-circuit ratio. The method includes: constructing an equivalent model of the integrated / grid-connected hybrid system; calculating the improved short-circuit ratio of multiple renewable energy power plants based on the voltage source characteristics of grid-connected equipment to quantify the grid strength at each grid connection point; constructing a characteristic polynomial based on the impedance matrix; and using the circular loop theorem to quickly search for the dominant eigenvalues, avoiding high-dimensional calculations, to obtain the critical short-circuit ratio. If the real-time short-circuit ratio is lower than the critical value, an instability risk is determined, triggering a control strategy that increases the capacity of grid-connected equipment or adjusts the grid connection point. This method, through the combination of the improved short-circuit ratio and the circular loop theorem, achieves online quantitative assessment and closed-loop control of the small-disturbance stability of integrated / grid-connected hybrid systems.

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.

The application discloses a short-circuit ratio adaptive new energy station reactive power and voltage cooperative control method and system, belongs to the new energy power generation control technical field, and is particularly suitable for wind power cluster control under a weak power grid environment. The voltage and current responses of a grid-connected point are collected to estimate the short-circuit ratio of the grid-connected point in real time; the droop gain and filter parameters of a voltage control loop are dynamically adjusted based on the short-circuit ratio; at the reactive power distribution level, the reactive power distribution coefficient is calculated by combining the current operating condition of the new energy equipment through a dynamic weighting strategy of real-time available capacity, and a distribution dead zone is eliminated through a deviation iterative redistribution algorithm; the optimized reactive power reference value is converted into a local voltage correction amount, and the deep integration of station-level centralized scheduling and unit-level rapid response is realized. The application effectively solves the problems of response delay, voltage out-of-limit and subsynchronous oscillation of the traditional PQ control under a weak power grid, and significantly improves the low voltage ride-through capability and grid-connected stability of the new energy station.

This invention provides a method, system, device, and medium for power output arrangement of flexible DC receiving-end converter stations. The method includes: acquiring power flow data of the receiving-end power grid connected to at least one target flexible DC system; wherein the target flexible DC system includes multiple receiving-end converter stations to be solved; using the power output of each receiving-end converter station as a variable and determining it as a particle component; iteratively solving each particle using a particle swarm optimization algorithm to obtain the boundary power output; wherein the fitness function is expressed as the minimization of the generalized short-circuit ratio of the system operation, and the generalized short-circuit ratio of the system operation is calculated based on the power flow data; determining the control power, and then realizing the power output arrangement of each receiving-end converter station of the target flexible DC system based on the control power. This invention uses a particle swarm optimization algorithm for iterative optimization, avoiding the problem of low solution efficiency of traditional exhaustive methods when facing massive power output combinations, significantly shortening the optimization time, and improving the response speed of converter station power output arrangement adjustment.

The application discloses a voltage source current source dual-mode switching control method and system, and a storage medium, and belongs to the technical field of power system control. The method comprises the following steps: acquiring operation state data of each energy storage unit, adopting improved mixed integer linear programming to optimize a switching state and determining a voltage source starting state; introducing control based on direct-current voltage synchronization into hierarchical optimization cooperative control to realize self-synchronization of equivalent voltage sources of each unit; generating a mode switching signal based on real-time short-circuit ratio detection and hysteresis interval discrimination of ports of each unit; starting distributed pre-synchronization control to realize smooth transition between current source type and voltage source type; executing smooth switching, starting phase-locked loop control to complete resynchronization after recalculating the switching state. The application combines the wide frequency response characteristics of hybrid energy storage and the topological variable capability of a reconfigurable network, realizes disturbance-free switching, and improves the ability to cope with strong and weak network changes.

This invention discloses a method and system for analyzing the static voltage stability of an LCC-HVDC receiving-end power grid. The method employed is as follows: based on a quasi-steady-state mathematical model of the AC / DC system, the power balance equation and the AC system power flow equation are simultaneously established to obtain the power-voltage relationship equation; partial derivatives of the power-voltage relationship equation with respect to voltage and reactive power are obtained to determine the voltage sensitivity to reactive power changes, i.e., the voltage stability index VSI; to describe the voltage stability at the critical steady state of the system, the curve of DC power versus DC current is set to its highest point, and the effective short-circuit ratio at this point is defined as the generalized critical effective short-circuit ratio (GCESCR); based on the GCESCR, the impact of different control modes of the asynchronous power supply on static voltage stability is analyzed. This invention can more accurately describe the voltage support strength of the LCC-HVDC receiving-end AC power grid after the asynchronous power supply is connected.

The embodiment of the application provides a kind of receiving end power grid DC carrying capacity multidimensional evaluation method and system, it is related to new energy power grid technical field.The method is based on the transient short-circuit capacity function of new energy low voltage ride through control characteristic and synchronous machine short-circuit current transient process.Establish the improved short-circuit ratio index again, to pass through the curve characteristics corresponding to the improved short-circuit ratio index extraction, construct voltage intensity comprehensive evaluation function.Then establish the evaluation model of receiving end power grid DC carrying capacity, and according to basic particle swarm algorithm, the evaluation model is executed iteration solution, to obtain evaluation result information.The method can form improved short-circuit ratio index by introducing transient short-circuit capacity function and new energy short-circuit capacity reliability coefficient, for dynamic quantification transient voltage support intensity, and by establishing evaluation model, form efficient evaluation mechanism suitable for high proportion new energy receiving end power grid scene under DC feed-in carrying capacity, improve the accuracy of evaluation result.

This invention discloses a hybrid damping adaptive control method for grid-connected inverters that considers the short-circuit ratio, belonging to the field of power conversion technology. The steps include: constructing a three-phase grid-connected inverter main circuit system; obtaining an error signal by subtracting the inverter grid-connected current from a reference current, and using the error signal as the input to a quasi-resonant controller; and obtaining a feedforward signal u from the capacitor current through an improved hybrid damping control loop. hr An adaptive control equation consisting of the short-circuit ratio λ, passive weighting coefficient K1, and active weighting coefficient K2 is introduced. Optimal hybrid damping control parameters K1 and K2 are generated based on the real-time detected value of the short-circuit ratio λ. The output signal u of the quasi-resonant controller is then... pr Subtract the feedforward signal u hr The modulation signal is obtained; the modulation signal is compared with the carrier control signal to control the switching on and off of the three-phase inverter power transistors. This invention, applied to LCL-type grid-connected inverter systems, can adapt to a wide range of grid strength variations, maintain sufficient phase margin in the system, and improve system stability.

The application discloses a kind of flexible interconnection power distribution system fault-based multi-factor comprehensive evaluation master / slave station optimization switching method, comprising: 1, master station is converted to V / F control after power failure to support load, and the load power is calculated;2, by calculating the short-circuit ratio of slave station, determine that the system is in strong network or weak network environment;3, in strong network environment, screening is carried out according to power stability limit curve and controller parameter;4, in weak network environment, compare the power limit of each station by power transmission deviation threshold;5, select the site with the minimum line loss in the whole network as the new master station, switch to the constant DC voltage control, and the remaining sites maintain PQ control, so as to realize the optimization switching under fault state.The application takes stability as the premise, optimizes the master station by differentiated power grid environment evaluation, can reduce loss, improve operation efficiency, solve the parameter mismatch and power limitation problem in strong and weak network switching, and enhance the system fault self-healing reconstruction and steady-state operation ability.

This invention discloses a hybrid control method and system for converters integrated with grids. Specifically, it analyzes the inherent structural differences between grid-connected GFL and grid-connected GFM converter controls, constructing a GFL-GFM hybrid control model based on a shared dual-inner-loop architecture. It calculates the stability intervals of GFL and GFM control under different short-circuit ratios (SCRs), and determines the switching thresholds for GFL, GFM, and hybrid control modes based on the stability boundaries. Based on the stability regions of GFL and GFM modes, it determines the upper and lower SCR thresholds, and employs a hysteresis-based adaptive hybrid control strategy to dynamically adjust the hybrid weights according to SCR changes. This invention achieves stable operation and zero-disturbance switching of the converter under three control modes: grid-connected control, grid-connected control, and hybrid control. It effectively controls the voltage amplitude near the rated value, ensuring a high-quality power supply.

The application discloses a high-proportion new energy power system energy storage configuration method and system, and belongs to the technical field of energy storage. The scheme is as follows: firstly, a target system power flow and stability calculation model containing a high proportion of new energy is established; based on this, weak nodes in the system are calculated and identified. Then, for the weak nodes, multi-dimensional index information reflecting the transient stability of the system is obtained through stability analysis, including short-circuit ratio, frequency change rate and oscillation damping ratio. Then, taking the minimum total capacity of energy storage and the maximum comprehensive stability margin of the system as the target, an optimization model is constructed and solved based on the multi-dimensional index information. Finally, the recommended configuration capacity of the network type and the network following type energy storage satisfying the safety and stability constraints is output. The application realizes scientific and quantitative configuration of energy storage not dependent on historical data and facing multiple stability constraints.

The application discloses a network-constructed flexible direct current converter power oscillation suppression method, device, equipment and medium, and belongs to the field of power grid equipment control. The method is as follows: according to oscillation characteristic information under a plurality of preset short-circuit ratio conditions, a target oscillation mode is determined from an oscillation mode corresponding to each short-circuit ratio condition; wherein the oscillation characteristic information comprises characteristic roots and characteristic vectors of a plurality of state variables corresponding to each control link; according to the characteristic vectors, a participation factor of each state variable to the target oscillation mode is calculated to identify a target control link causing power oscillation; according to the characteristic roots, a sensitivity of each control parameter in the target control link to the target oscillation mode is calculated to screen a plurality of to-be-optimized control parameters; and an optimized value of each to-be-optimized control parameter is determined in a feasible region, and the corresponding control link is controlled through the optimized value to suppress power oscillation. The application can improve the accuracy of network-constructed flexible direct current converter power oscillation suppression.

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 kind of converter follow network hybrid control method and system, specifically for: analysis follows network type GFL and the inherent structural difference of GFM converter control of network type, constructs GFL-GFM hybrid control model based on shared double inner ring architecture;The stable interval of GFL and GFM control under different short-circuit ratio SCR is calculated, and the switching threshold of GFL, GFM and three modes of hybrid control is determined based on stability boundary;Determine the upper and lower threshold of SCR based on the stability region of GFL and GFM mode, adopt the follow network hybrid adaptive control strategy based on hysteresis mechanism, and dynamically adjust the follow network hybrid weight according to the change of SCR.The application realizes the stable operation and zero disturbance switching of converter in follow network control, network control and follow network hybrid control three modes, can effectively control voltage amplitude near rated value, and ensure high-quality power supply.

The application provides a control method of a static var generator with the capability of maintaining the grid strength of a virtual synchronous generator, and relates to the electrical technical field.The core of the method is that the static var generator increases a control link of a current or voltage instruction value on the basis of traditional double-loop control, the control link calculates the grid inductance parameter in real time according to the operation state of the virtual synchronous generator and the grid strength, flexibly regulates and controls the instruction value of the static var generator, the static var generator combines the instruction value to carry out current loop control, coordinate transformation and PWM modulation, and finally outputs corresponding voltage and current, when the system is disturbed, the static var generator adjusts the reactive power output by changing the instruction value, so that the short-circuit ratio before and after the system is disturbed remains unchanged, thereby maintaining the grid strength of the grid connection point of the virtual synchronous generator, supporting the stable operation of the virtual synchronous generator, and improving the grid connection stability of the virtual synchronous generator.

The application discloses a static voltage stability limit calculation method, device and equipment, wherein the method comprises the following steps: constructing a small system model based on the structure that a new energy power supply, a new energy box-type transformer, a reactive power compensation device and an infinite system are sequentially connected; calculating the short-circuit capacity of the new energy terminal by using system impedance; then determining the short-circuit ratio of the new energy terminal; establishing the quantitative relationship of the system impedance, the short-circuit ratio and the rated capacity of the new energy; determining the grid connection point impedance based on the quantitative relationship and the relationship of the equivalent reactance of the new energy box-type transformer; establishing the mapping relationship between the power factor angle and the capacitive reactive power compensation provided by the reactive power compensation device; and calculating the static voltage stability limit based on the mapping relationship, the voltage of the new energy terminal and the grid connection point impedance. The application forms a static voltage stability limit calculation mode represented by the short-circuit ratio and the reactive power compensation capacity, and accurately improves the contribution of the short-circuit ratio and the reactive power compensation capacity to the static voltage stability limit.

This invention discloses a method, apparatus, electronic device, and medium for assessing the system strength of a power system, addressing the problems of high computational complexity, large errors, and limited application in large-scale real-world power grids in current related technologies. The power system comprises multiple grid-connected devices; each grid-connected device corresponds to one network-building device. The invention obtains the power system grid admittance matrix, the operating output and critical short-circuit ratio of each grid-connected device under current operating conditions, and the equivalent impedance of each network-building device. A matrix transformation based on node admittance correction is performed using the grid admittance matrix and each equivalent impedance to obtain the grid admittance matrix. The generalized operating short-circuit ratio is calculated based on the grid admittance matrix and each operating output. A generalized operating short-circuit ratio threshold is calculated based on each critical short-circuit ratio, considering the participation factors of multiple grid-connected devices on the generalized operating short-circuit ratio. The system strength is assessed based on the generalized operating short-circuit ratio and the generalized operating short-circuit ratio threshold.

This invention discloses an adaptive grid-connected control method, system, and control device for converters, aiming to solve the technical problems of insufficient adaptability of existing converter control technologies across a wide short-circuit ratio range and difficulties in switching between grid-connected and off-grid operation. The invention includes: determining the total number of modes and defining mode boundaries based on the range of grid operating state changes; obtaining grid sampling information, identifying the grid operating state by detecting equivalent grid parameters, determining the grid's off-grid or on-grid state and short-circuit ratio, and determining the modes; determining the corresponding modes based on the identification results, and adaptively adjusting three sets of control parameters: voltage loop, current feedforward compensation, and current loop; finally generating modulation commands, and generating modulation signals to control the power switches based on the control commands. This invention, through a multi-mode adaptive control strategy, achieves stable operation of the converter under different operating conditions in off-grid, weak grid, and strong grid environments, effectively improving the reliability of new energy grid connection and grid stability.

The application provides a source-grid coordination planning method considering short-circuit ratio constraints of new energy multi-station, comprising: obtaining a new energy multi-station short-circuit ratio expansion constraint model; constructing a three-stage source-grid coordination planning model; fusing the new energy multi-station short-circuit ratio expansion constraint model as a constraint of the three-stage source-grid coordination planning model; solving the three-stage source-grid coordination planning model with the fused constraint, and outputting a system configuration scheme. The method provided in the application constructs a three-stage planning model covering new energy site selection and capacity determination, network expansion and operation verification, and guides new energy to preferentially access high-intensity areas of the power grid through short-circuit capacity weight, and takes into account the economy and system voltage safety level of the planning scheme.

The application discloses a new energy power grid active control method and device considering voltage support capability and belongs to the technical field of power system stability analysis and control. By constructing a reactive power capacity new energy multi-station short-circuit ratio index, the voltage support strength of a high proportion new energy power grid is accurately evaluated; after a power grid fault, a power source homophonic grouping constraint is established according to a multi-type power source grouping result, and a voltage support strength constraint of an islanded sub-system is constructed; the optimal solution section search model of active control is established by comprehensively considering the homophonic grouping constraint and the voltage support strength constraint, and the optimal solution section and the islanded sub-system control scheme are obtained by solving the model. The defects that the traditional active solution section control method does not consider the voltage support capability are overcome, the short-circuit ratio index is taken as a constraint and is integrated into the control model, the islanded sub-system has sufficient voltage support strength before and after active control is ensured, and the safe and stable operation level of the high proportion new energy power grid is effectively improved.

This application discloses an adaptive impedance matching method for short-circuit ratio in GIL-overhead hybrid lines, belonging to the field of power system technology. This method calculates the real-time short-circuit ratio by collecting voltage and current phasors at the connection point; calculates a weighting factor based on the real-time short-circuit ratio and a threshold comparison, dynamically generating a two-stage target impedance; calculates the target inductance value and integrates GIL parasitic capacitance compensation to calculate the target capacitance value; converts the parameters into control commands to drive the actuator adjustment, and performs hysteresis comparison and voltage verification. This invention achieves an adaptive balance between precise matching of strong grids and voltage stability in weak grids by dynamically adjusting LC parameters based on the real-time short-circuit ratio. It utilizes a two-stage LC structure to suppress overvoltage and integrates parasitic capacitance to optimize volume and cost. The hysteresis and voltage verification mechanisms avoid frequent operation, improving system stability and equipment lifespan, providing a solution that balances insulation protection and transmission capacity for hybrid lines.

This invention discloses a method and system for testing the short-circuit ratio adaptability of a grid-connected power electronic converter based on secondary-side cascaded circuitry, belonging to the field of power testing technology. The method includes: performing an equivalent circuit for short-circuit ratio adaptability testing of a grid-connected power electronic converter based on the Thevenin / Norton equivalent circuit, and obtaining the equivalent results; based on the equivalent results, structurally adjusting the typical short-circuit ratio adaptability testing circuit to construct a secondary-side cascaded short-circuit ratio adaptability testing circuit for the grid-connected power electronic converter; and performing an adaptability test on the short-circuit ratio of the grid-connected power electronic converter based on the secondary-side cascaded short-circuit ratio adaptability testing circuit. This invention can evaluate the control strategy, dynamic performance, and grid-connected stability of grid-connected converters, providing key testing basis and verification means for their deployment, parameter tuning, and operating range delineation in real power grids.

The application discloses a control method for a phase-locked loop-network type MMC converter station power supply system. The control method adopts a constant AC voltage amplitude and active power, the MMC is kept synchronous with an AC power grid through a phase-locked loop, the q-axis voltage control link adjusts the d-axis current reference value according to the q-axis voltage and the active current reference value, so as to adjust the active power and keep the angular frequency and power angle stable; the d-axis voltage control link adjusts the q-axis current reference value according to the d-axis voltage, so as to adjust the reactive power and keep the PCC voltage stable. The application introduces a frequency deviation to adjust the active current reference value, so that the MMC output active power can respond to the frequency change, and the MMC has a primary frequency modulation characteristic; the phase-locked loop-network type MMC converter station is suitable for both a strong power grid with a relatively large short circuit and a weak power grid with a relatively small short circuit, and can delay the power output when the power instruction value or the power grid frequency changes, so that the application has good steady-state performance and transient performance.

The application discloses a subsynchronous oscillation monitoring device distribution method and device and a medium, and belongs to the technical field of power systems and their automation. In the power system, the proportion of wind power access is rising, and the risk of subsynchronous oscillation of the power grid is increasing. In order to effectively inhibit the spread of oscillation, it is necessary to configure a subsynchronous oscillation monitoring device in the power grid. Based on the new energy grid connection point with relatively low grid connection short-circuit calculated offline, the sub-super current components are injected into the power grid side from the station side, the subsynchronous oscillation propagation characteristics in the power grid are obtained, and the key nodes in the power grid which are strongly related to the subsynchronous oscillation are identified, and the monitoring device is configured. The application comprehensively considers the local weak nodes of new energy grid connection and the subsynchronous oscillation propagation characteristics, gives an oscillation monitoring device distribution scheme, and takes into account the economy of the monitoring system while ensuring the ability of the power grid to cope with the risk of subsynchronous oscillation.

The application discloses a grid strength evaluation-based follow-grid-construct-grid switching control method and specifically relates to the control field, and comprises the following steps: S1, a power grid and power plant state monitoring system is built, and core parameters required for control are initialized; S2, power grid and power plant operation data are collected in real time through the monitoring system, and key deviation parameters are obtained based on effective data; S3, a power grid strength comprehensive evaluation index containing a dynamic correction term is constructed through multidimensional analysis; S4, an operation state adaptability index is constructed through safety and stability analysis; and S5, a switching discrimination function is constructed based on the power grid strength comprehensive index and the operation state adaptability index, and a follow-grid-construct-grid switching time is dynamically decided. Through construction of the power grid strength comprehensive evaluation index which integrates a short-circuit ratio, a voltage support coefficient and a frequency stability coefficient, the application realizes accurate depiction of the power grid state, provides a reliable basis for switching decision, and improves the matching degree of the control mode and the power grid working condition.

The application discloses a kind of water and wind coupling system external sending capacity evaluation method, system and storage medium, establishes the maximum of system direct current external sending channel total power as objective function of direct current external sending capacity evaluation model, and determines unit output, direct current channel external sending power, node voltage and other core decision variables;Coupling linearization ac power flow constraint to accurately quantify node actual voltage and system power flow distribution, and then build the improved new energy multi-station operation short-circuit ratio constraint covering actual node voltage phasor and new energy injection power, for the strong nonlinear calculation bottleneck of this constraint, using the iterative tangent plane method based on improved SVM active learning, the complex nonlinear operating boundary is reconstructed into linear constraint that can be efficiently calculated, to obtain the optimal direct current external sending scheme that can guarantee voltage support strength.The precision and reliability of the external sending capacity evaluation conclusion are improved.