6 results about "Transient stability assessment" patented technology

This invention relates to the field of power electronic converter control technology and discloses a method and apparatus for judging the transient stability of a hybrid system with a grid-connected converter. The method includes constructing an equivalent model of the hybrid system comprising a grid-connected converter and a network-connected converter, wherein a virtual impedance is connected in series in the branch of the network-connected converter; constructing a Lyapunov energy function based on the equivalent model, wherein the independent variables include the power angle and phase-locked loop frequency of the grid-connected converter, and the power angle, frequency, and voltage amplitude of the network-connected converter; determining the stability domain boundary of the hybrid system using the Lassel invariant set principle when the derivative of the energy function with respect to time is less than or equal to 0; calculating the critical range of the virtual impedance based on the changing trend of the stability domain boundary, and determining the target value of the virtual impedance to maintain the transient stability of the hybrid system. The above method achieves quantitative judgment and parameter tuning of the transient stability of the hybrid system.

This invention discloses a method and system for transient stability assessment of new energy systems based on machine learning and data-driven approaches. It includes: performing time-domain simulations of electromechanical and electromagnetic transient models of the new energy system to obtain a sample set; constructing a system stability classification model based on a long short-term memory network; training the system stability classification model using a data-driven method; and achieving the assessment of electromagnetic transient stability through monitoring curves from electromechanical transient simulations. This invention establishes a mapping relationship between electromechanical and electromagnetic time scales through data-driven approaches, enabling the prediction of system stability at the electromagnetic transient scale based solely on the system's operation at the electromechanical transient scale. This solves the dual problems of low accuracy in electromechanical transient modeling of high-proportion new energy systems, which fails to accurately reflect real instability scenarios, and slow and inefficient electromagnetic transient simulation, thus achieving transient stability assessment of new energy systems.

This application provides a model building method, evaluation method, and system for power grid time-series stability assessment with high accuracy and strong interpretability. The model building method includes: initializing an Informer encoder; initializing a multivariate decision tree improved model; acquiring multidimensional time-series data after power grid disturbances and simultaneous system static feature data, processing them separately to obtain fixed-dimensional transient time-series feature vectors and static feature vectors; concatenating and fusing the fixed-dimensional transient time-series feature vectors and static feature vectors using a dimension superposition method to form a fused feature vector; inputting the fused feature vector into the initialized multivariate decision tree improved model for iterative training to obtain the power grid time-series stability assessment results and decision path results. This application generates a highly accurate power grid time-series stability assessment tool with a trustworthy decision-making process, providing efficient and accurate guidance for power grid time-series stability assessment. It is applicable to the technical field of transient stability assessment.

This invention relates to the field of transient stability assessment technology for converters, providing a method and system for angular frequency limiting tuning to ensure the global stability of grid-connected converters. The method includes extending the single-pendulum deceleration process of a virtual synchronous machine into a multi-pendulum deceleration process, and determining the upper limit of the angular frequency limiting based on the stability conditions of the multi-pendulum. During the single-pendulum deceleration process of the virtual synchronous machine, the effects of potential energy and damping dissipation energy are considered simultaneously, and the damping dissipation energy is approximated and quantified using the concavity and convexity of the angular frequency trajectory. Based on the potential energy and the approximate quantified damping dissipation energy, the maximum upper limit of the required angular frequency limiting is solved using the deceleration critical stability condition of the last pendulum in the multi-pendulum deceleration process, thus completing the transient stability assessment technology of angular frequency limiting tuning to ensure the global stability of the grid-connected converter. It can use angular frequency limiting control to ensure that the virtual synchronous machine recovers synchronous and stable operation at least within the period of a single pendulum, while simultaneously considering the damping effect to obtain a larger upper limit of the angular frequency limiting tuning.

This application discloses a method and apparatus for transient stability assessment of ultra-high voltage AC transmission systems. The method includes: acquiring process noise, measurement noise, a first parameter, and measurement data; integrating and modeling to obtain a state-space equation; obtaining real-time estimates of state variables through extended Kalman filter dynamic state estimation; determining the specific location of the oscillation center after frequency extraction and linear fitting; obtaining an equivalent system through mirror simplification based on the specific location; calculating the energy function value; and comparing the energy function value with a preset stable energy threshold at the critical moment of system fault clearing to determine the transient stable state of the system. This application improves the accuracy and robustness of assessment under non-Gaussian noise scenarios, adapts to the online assessment needs of ultra-high voltage AC transmission systems, and provides technical support for the safe and stable operation of the power grid.

This invention discloses a method for obtaining a robust transient stability assessment model based on temporal transfer learning. The method includes: in an initial stage, selecting a set of key curves from the training samples of the original scenario and using them as training samples for a data-driven transient stability assessment model; applying z-score normalization to the training samples, inputting the normalized training samples into a temporal neural network, and pre-training the data-driven transient stability assessment model by minimizing the classification loss; in a second stage, classifying the training samples into multiple categories based on labels, and within each category, dividing the training samples into multiple groups through clustering, combining the classification loss and temporal distribution matching loss to obtain a comprehensive training loss, and training by minimizing the comprehensive training loss to finally obtain the transient stability assessment model. This invention enhances the generalization performance of the data-driven model for transient stability assessment of power systems of different scales without requiring target domain samples, exhibiting strong robustness.