| With the increasing scale and complexity of interconnected systems,the elements of the system are diversified.The components are closely related and interacted with each other,and the uncertainties of power grid operation increases.At the same time,the rapid development of clean energy driven by the energy production and the revolution of consumption has increased the fluctuation of system operation parameters,and the occasional accidents are inevitable.The faults brought about by the randomness and unpredictability of the system have gradually evolved into the complex results with multiple links.The frequent changes of the system operation mode lead to a large degree of inadaptability of off-line transient stability prediction methods for complex systems.The transient stability discrimination and the emergency control device action lack of synergy and the process of the formulation and selection of the off-line control strategy is slightly rough.Therefore,the establishment of accurate on-line transient stability quantification method is an important guarantee for the safe and stable operation of power system.The actual operation of the protection device is closely related to the transient stability of the system.However,the current research on relay protection and the transient stability analysis of the system are separated from each other.To solve this problem,a series of on-line quantitative assessment methods for transient stability margin predicting the safe operation of the system based on protection informations are proposed in this paper.This method establishes a communication channel between relay protection and transient stability analysis,takes into account the information of protection action,and quantifies the transient stability of the system after fault on-line.Firstly,the existing research methods of transient stability are summarized and compared,the application scope and drawbacks of different methods are elaborated in detail,the necessity of on-line evaluation of transient stability margin is discussed,and a refined control strategy based on the actual action information of protective devices and stable operation state is proposed-By means of multi-dimensional fault panoramic information,a system stability boundary model with advanced evaluation function is established.Then,based on the energy function,a practical calculation method of the system trajectory function relation with high prediction accuracy is proposed.Compared with the simulation results,the trend coincidence of the stable boundary between the two methods is very high,which verifies the correctness of the practical calculation method.The derived angle calculation formula is applied to the construction of energy function.And the simulation results show that it has a high accuracy in energy calculation and stability margin measurement.Finally,a transient stability margin analysis method based on LASSO regression algorithm is proposed to solve the problem that the system structure model is difficult to obtain or the clustering characteristics of multi-machine systems are not obvious.Based on the efficient processing of large data,the regression calculation of the data is realized by machine learning method,and the advanced prediction of the critical clearing time and the online evaluation of the stability margin are completed by taking the critical clearing time as the sample index.The simulation results show that the calculation error,false alarm rate and leakage alarm rate are acceptable. |
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