A New Method to Determine the Optimal Location and Amount of Shed Load in Multi-Stage Under Frequency Load Shedding Using DIgSILENT

Under-frequency load shedding (UFLS) appears to be an effective approach to preventing cascading outages that includes various methods. In recent years, much research has been done in the field of dynamic schemes. However, these schemes are less commonly used due to their disadvantages such as the inability to calculate the optimal shed load amount, the need to additional relays or communication infrastructures, etc. In contrast, static UFLS schemes are more common due to their simplicity, efficiency, fast implementation, as well as the unnecessity of additional equipment. However, how to determine the load shedding (LS) location and amount in static methods seems to be still challenging. Furthermore, conventional methods have a major drawback because of over shedding. In order to solve this problem, in this paper, a new static method is proposed to determine the location and amount of optimal LS based on co-simulation of DIgSILENT and MATLAB software. The system dynamics is simulated in DIgSILENT and optimization using imperialist competitive algorithm (ICA) runs in MATLAB. This co-simulation makes it possible to take advantage of both pieces of software. The results of the simulation on the IEEE 39-Bustest system in several scenarios clearly demonstrate the efficiency of the proposed method.