Dynamic Security and Stability Region under Different Renewable Energy Permeability in IENGS System

The integration of renewable energy sources (RESs) remains growing rapidly in recent years. At the same time, security problems after contingencies were attracting great attention, due to deficiencies for the stable operation, even could induce the collapse of integrated energy systems with the deep interconnection of such RESs. To existing issues, the hyper-plane (HP) expression is proved to be an excellent tool for power system situational awareness and stability-constrained operation in practical dynamic security stability regions (PDSSR). In this study, a concept and model were proposed for a high renewable energy penetration of integrated electricity-natural gas system (HRE-IENGS) based on the $N-1$ security guideline. The scheme instruction and system evaluation processes as follows: in order to improve the accuracy of the IENGS system, simulation fitting solutions of PDSSR boundary were presented according to a hybrid algorithm, including dynamic self-adaptive differential evolution algorithm (DSADE), and a least square support vector machine (LSSVM) algorithm. The adopted algorithm approach was applied to rapid approximating of the PDSSR boundary by HP expression in power injection spaces. Simultaneously, different renewable energy permeabilities (DREPs) were set from 5 to 50 %, and active power injections of DREPs under short circuit fault on IEEE 118 bus system simulated by using DIgSLENT/power factory software. As the consequence, this mentioned method effectively described the security stability boundary of HRE-IENGS, and realized the three-dimensional visualization space of DREPs-PDSSR. In addition, the behavior of operation points and PDSSR under DREPs were carefully investigated, and unstable runs were accurately exposed. Through the PDSSR, the state analysis could be conducted rapidly on several parameters, including security and stability assessment with various energy supply capabilities. Meanwhile, these indexes were calculated offline and applied on-line. The results of this study verified the accuracy and effectiveness of the proposed modeling for the considered system, and thus could provide technical support for the stability of the HRE-IENGS system.