Intelligent Assessment of dynamic Security in Distribution Networks with High Penetration Levels of Intermittent Decentralized Generating Units

Felipe Castro
The integration of decentralized energy resources is changing the ways in which distribution networks are operated. A major change is the implementation of active control strategies to adapt to this energy transition. The dynamic nature of these controllers and the supply uncertainty of these sources require for the operators to count with tools to assess the system security at all times, just as it is done in the transmission level through a “Dynamic Security Assessment” (DSA). DSA is a topic that has widely been studied and adopted in transmission systems to face power system related issues, mostly without considering possible IT/ICT related issues. In this sense, this thesis fills the literature gap of DSA in active distribution networks while facing events (both from the power system and its ICT infrastructure), or for determining its optimal dynamic operation. Indeed, the number of active actors in the network creates a playground for large scale unintended (i.e. contingencies) or intended (i.e. cyber-attacks) disturbances, resulting in security risks that require fast and effective assessment tools. Based on the above, the aim of this work is to define high level guidelines that allow simplifying DSA in distribution networks, through the implementation of a methodology to determine the interactions of the network with its controllers. The focus of these guidelines is kept in the computational component, by reducing the number of dynamic simulations, as well as the number of active controllers required for DSA. The inputs of these guidelines are obtained based on the analysis of controllers represented by the standard IEC61499, and the variables of the power system under assessment. Based on this information a Controller Influence Chart (CIC) is defined, and it is processed in DSA simplification guidelines proposed in this work. The guidelines are assessed through two performance metrics: its efficacy, which relates to the accuracy with which the guidelines detect controllers and simulations that may be discarded; and efficiency, which relates to the proportion of the controllers and simulations that the guidelines identify as insignificant for DSA, compared to the real amount of insignificant controllers and simulations.The results of the implementation of these guidelines in a 242-busbar distribution show that DSA is performed with 42 out of a total of 48 simulations, in which 18 of them, a total of 124 out of a 245 controllers are active. By the analysis of the dynamic simulations, this results in a efficacy of 100% and an efficiency of 21,4%. Although the efficacy is optimal, the low efficiency is caused by the limitations imposed by the generality of the method.Future proposed work includes the automation of these guidelines, as well as its extensions to further ICT related events, such as cyber-attacks and probabilistic communication issues.
February / 2018
Smart Grid Cyber-Resilience Labor